diff --git a/libs/horizon/src/androidTest/java/com/instructure/horizon/ui/features/inbox/HorizonInboxComposeUiTest.kt b/libs/horizon/src/androidTest/java/com/instructure/horizon/ui/features/inbox/HorizonInboxComposeUiTest.kt
index 8f0a0950d9..4266ee31d8 100644
--- a/libs/horizon/src/androidTest/java/com/instructure/horizon/ui/features/inbox/HorizonInboxComposeUiTest.kt
+++ b/libs/horizon/src/androidTest/java/com/instructure/horizon/ui/features/inbox/HorizonInboxComposeUiTest.kt
@@ -54,7 +54,7 @@ class HorizonInboxComposeUiTest {
             HorizonInboxComposeScreen(uiState, pickerState, rememberNavController())
         }
 
-        composeTestRule.onNodeWithContentDescription("Select Course")
+        composeTestRule.onNodeWithContentDescription("Course")
             .assertIsDisplayed()
     }
 
diff --git a/libs/horizon/src/main/java/com/instructure/horizon/features/inbox/compose/HorizonInboxComposeScreen.kt b/libs/horizon/src/main/java/com/instructure/horizon/features/inbox/compose/HorizonInboxComposeScreen.kt
index 47fc1f97e3..e4a64e4c0b 100644
--- a/libs/horizon/src/main/java/com/instructure/horizon/features/inbox/compose/HorizonInboxComposeScreen.kt
+++ b/libs/horizon/src/main/java/com/instructure/horizon/features/inbox/compose/HorizonInboxComposeScreen.kt
@@ -47,8 +47,6 @@ import androidx.compose.ui.Alignment
 import androidx.compose.ui.Modifier
 import androidx.compose.ui.platform.LocalContext
 import androidx.compose.ui.res.stringResource
-import androidx.compose.ui.semantics.contentDescription
-import androidx.compose.ui.semantics.semantics
 import androidx.compose.ui.tooling.preview.Preview
 import androidx.compose.ui.unit.dp
 import androidx.core.content.ContextCompat
@@ -168,13 +166,14 @@ private fun HorizonInboxComposeTopBar(
                 stringResource(R.string.inboxComposeTitle),
                 style = HorizonTypography.h2,
                 color = HorizonColors.Text.title(),
-                modifier = Modifier.padding(horizontal = 12.dp)
+                modifier = Modifier
+                    .padding(horizontal = 12.dp)
             )
         },
         actions = {
             IconButton(
                 iconRes = R.drawable.close,
-                contentDescription = null,
+                contentDescription = stringResource(R.string.close),
                 color = IconButtonColor.Inverse,
                 elevation = HorizonElevation.level4,
                 onClick = {
@@ -274,13 +273,7 @@ private fun CourseRecipientPickerSection(state: HorizonInboxComposeUiState) {
             onMenuOpenChanged = { isRecipientPickerOpened = it },
             minSearchQueryLengthForMenu = state.minQueryLength
         )
-        val context = LocalContext.current
-        MultiSelectSearch(
-            recipientPickerState,
-            Modifier.semantics {
-                contentDescription = context.getString(R.string.a11y_inboxComposeSelectCourse)
-            }
-        )
+        MultiSelectSearch(recipientPickerState)
 
         HorizonSpace(SpaceSize.SPACE_12)
     }
diff --git a/libs/horizon/src/main/java/com/instructure/horizon/features/inbox/details/HorizonInboxDetailsScreen.kt b/libs/horizon/src/main/java/com/instructure/horizon/features/inbox/details/HorizonInboxDetailsScreen.kt
index 7e63437e3e..184945be90 100644
--- a/libs/horizon/src/main/java/com/instructure/horizon/features/inbox/details/HorizonInboxDetailsScreen.kt
+++ b/libs/horizon/src/main/java/com/instructure/horizon/features/inbox/details/HorizonInboxDetailsScreen.kt
@@ -21,6 +21,7 @@ import androidx.annotation.DrawableRes
 import androidx.compose.animation.AnimatedContent
 import androidx.compose.foundation.ExperimentalFoundationApi
 import androidx.compose.foundation.background
+import androidx.compose.foundation.layout.Arrangement
 import androidx.compose.foundation.layout.Box
 import androidx.compose.foundation.layout.Column
 import androidx.compose.foundation.layout.PaddingValues
@@ -31,7 +32,8 @@ import androidx.compose.foundation.layout.fillMaxWidth
 import androidx.compose.foundation.layout.padding
 import androidx.compose.foundation.layout.size
 import androidx.compose.foundation.lazy.LazyColumn
-import androidx.compose.foundation.lazy.items
+import androidx.compose.foundation.lazy.itemsIndexed
+import androidx.compose.foundation.lazy.rememberLazyListState
 import androidx.compose.material3.CenterAlignedTopAppBar
 import androidx.compose.material3.ExperimentalMaterial3Api
 import androidx.compose.material3.Icon
@@ -50,6 +52,8 @@ import androidx.compose.ui.draw.clip
 import androidx.compose.ui.platform.LocalContext
 import androidx.compose.ui.res.painterResource
 import androidx.compose.ui.res.stringResource
+import androidx.compose.ui.semantics.isTraversalGroup
+import androidx.compose.ui.semantics.semantics
 import androidx.compose.ui.text.input.TextFieldValue
 import androidx.compose.ui.tooling.preview.Preview
 import androidx.compose.ui.unit.dp
@@ -198,25 +202,39 @@ private fun HorizonInboxDetailsContent(
             .clip(HorizonCornerRadius.level4Top)
             .background(HorizonColors.Surface.pageSecondary())
     ) {
+        val scrollState = rememberLazyListState(
+            if (state.bottomLayout) {
+                state.items.lastIndex
+            } else {
+                0
+            }
+        )
         LazyColumn(
+            verticalArrangement = if (state.bottomLayout) Arrangement.Bottom else Arrangement.Top,
+            state = scrollState,
             modifier = Modifier
-                .fillMaxSize()
-                .background(HorizonColors.Surface.pageSecondary()),
-            reverseLayout = state.bottomLayout,
+                .weight(1f)
+                .background(HorizonColors.Surface.pageSecondary())
+                .semantics {
+                    isTraversalGroup = true
+                },
             contentPadding = PaddingValues(top = 16.dp)
         ) {
-            if (state.replyState != null) {
-                stickyHeader { HorizonInboxReplyContent(state.replyState) }
-            }
-            items(state.items) {
+            itemsIndexed(state.items) { index, item ->
                 Column {
-                    HorizonInboxDetailsItem(it)
-                    if ((state.bottomLayout && it != state.items.firstOrNull()) || (!state.bottomLayout && it != state.items.lastOrNull())) {
+                    HorizonInboxDetailsItem(
+                        item,
+                        Modifier.semantics(true) {}
+                    )
+                    if (item != state.items.lastOrNull()) {
                         HorizonDivider()
                     }
                 }
             }
         }
+        if (state.replyState != null) {
+            HorizonInboxReplyContent(state.replyState)
+        }
     }
 }
 
@@ -448,7 +466,6 @@ private fun HorizonInboxDetailsScreenPreview() {
                 onReplyTextValueChange = {},
                 onSendReply = {}
             ),
-            bottomLayout = true
         )
     )
 }
\ No newline at end of file
diff --git a/libs/horizon/src/main/java/com/instructure/horizon/features/inbox/details/HorizonInboxDetailsViewModel.kt b/libs/horizon/src/main/java/com/instructure/horizon/features/inbox/details/HorizonInboxDetailsViewModel.kt
index 0beb4050f1..bbcbdda23e 100644
--- a/libs/horizon/src/main/java/com/instructure/horizon/features/inbox/details/HorizonInboxDetailsViewModel.kt
+++ b/libs/horizon/src/main/java/com/instructure/horizon/features/inbox/details/HorizonInboxDetailsViewModel.kt
@@ -134,7 +134,7 @@ class HorizonInboxDetailsViewModel @Inject constructor(
                                 attachment.toAttachmentUiState()
                             }
                         )
-                    },
+                    }.reversed(),
                     replyState = getReplyState(),
                     bottomLayout = true
                 )
@@ -382,7 +382,7 @@ class HorizonInboxDetailsViewModel @Inject constructor(
 
             _uiState.update {
                 it.copy(
-                    items = conversation.messages.map { message ->
+                    items = it.items + conversation.messages.map { message ->
                         HorizonInboxDetailsItem(
                             author = conversation.participants.firstOrNull { it.id == message.authorId }?.name.orEmpty(),
                             date = message.createdAt.toDate() ?: Date(),
@@ -392,7 +392,7 @@ class HorizonInboxDetailsViewModel @Inject constructor(
                                 attachment.toAttachmentUiState()
                             }
                         )
-                    } + it.items,
+                    },
                     replyState = it.replyState?.copy(
                         replyTextValue = TextFieldValue(""),
                         isLoading = false,
diff --git a/libs/horizon/src/main/java/com/instructure/horizon/features/inbox/list/HorizonInboxListScreen.kt b/libs/horizon/src/main/java/com/instructure/horizon/features/inbox/list/HorizonInboxListScreen.kt
index ce3e5977c6..08dddce21f 100644
--- a/libs/horizon/src/main/java/com/instructure/horizon/features/inbox/list/HorizonInboxListScreen.kt
+++ b/libs/horizon/src/main/java/com/instructure/horizon/features/inbox/list/HorizonInboxListScreen.kt
@@ -41,7 +41,6 @@ import androidx.compose.material3.pulltorefresh.PullToRefreshDefaults.Indicator
 import androidx.compose.material3.pulltorefresh.rememberPullToRefreshState
 import androidx.compose.runtime.Composable
 import androidx.compose.runtime.LaunchedEffect
-import androidx.compose.runtime.collectAsState
 import androidx.compose.runtime.getValue
 import androidx.compose.runtime.mutableStateOf
 import androidx.compose.runtime.remember
@@ -51,6 +50,8 @@ import androidx.compose.ui.Modifier
 import androidx.compose.ui.draw.clip
 import androidx.compose.ui.platform.LocalContext
 import androidx.compose.ui.res.stringResource
+import androidx.compose.ui.semantics.semantics
+import androidx.compose.ui.semantics.stateDescription
 import androidx.compose.ui.tooling.preview.Preview
 import androidx.compose.ui.unit.dp
 import androidx.core.content.ContextCompat
@@ -192,6 +193,7 @@ private fun LazyListScope.inboxHeader(
             ) {
                 IconButton(
                     iconRes = R.drawable.arrow_back,
+                    contentDescription = stringResource(R.string.a11yNavigateBack),
                     size = IconButtonSize.NORMAL,
                     color = IconButtonColor.Inverse,
                     elevation = HorizonElevation.level4,
@@ -338,9 +340,14 @@ private fun InboxContentItem(
     onClick: () -> Unit,
     modifier: Modifier = Modifier
 ) {
+    val readState = stringResource(R.string.a11y_readInboxMessage)
+    val unreadState = stringResource(R.string.a11y_unreadInboxMessage)
     Column(
         modifier = modifier
             .clickable { onClick() }
+            .semantics(true) {
+                stateDescription = if (item.isUnread) unreadState else readState
+            }
     ) {
         Column(
             modifier = Modifier
diff --git a/libs/horizon/src/main/java/com/instructure/horizon/horizonui/molecules/ActionBottomSheet.kt b/libs/horizon/src/main/java/com/instructure/horizon/horizonui/molecules/ActionBottomSheet.kt
index 2f60ea3e50..4696604e0a 100644
--- a/libs/horizon/src/main/java/com/instructure/horizon/horizonui/molecules/ActionBottomSheet.kt
+++ b/libs/horizon/src/main/java/com/instructure/horizon/horizonui/molecules/ActionBottomSheet.kt
@@ -42,6 +42,7 @@ import androidx.compose.ui.Modifier
 import androidx.compose.ui.draw.clip
 import androidx.compose.ui.platform.LocalContext
 import androidx.compose.ui.res.painterResource
+import androidx.compose.ui.res.stringResource
 import androidx.compose.ui.text.style.TextAlign
 import androidx.compose.ui.tooling.preview.Preview
 import androidx.compose.ui.unit.dp
@@ -86,6 +87,7 @@ fun ActionBottomSheet(
                 )
                 IconButton(
                     iconRes = R.drawable.close, color = IconButtonColor.Inverse,
+                    contentDescription = stringResource(R.string.a11y_close),
                     onClick = {
                         localCoroutineScope.launch {
                             sheetState.hide()
diff --git a/libs/horizon/src/main/java/com/instructure/horizon/horizonui/molecules/Tag.kt b/libs/horizon/src/main/java/com/instructure/horizon/horizonui/molecules/Tag.kt
index d622d0dfe6..62037256b4 100644
--- a/libs/horizon/src/main/java/com/instructure/horizon/horizonui/molecules/Tag.kt
+++ b/libs/horizon/src/main/java/com/instructure/horizon/horizonui/molecules/Tag.kt
@@ -36,6 +36,11 @@ import androidx.compose.ui.graphics.Color
 import androidx.compose.ui.platform.LocalContext
 import androidx.compose.ui.res.painterResource
 import androidx.compose.ui.res.stringResource
+import androidx.compose.ui.semantics.clearAndSetSemantics
+import androidx.compose.ui.semantics.disabled
+import androidx.compose.ui.semantics.hideFromAccessibility
+import androidx.compose.ui.semantics.onClick
+import androidx.compose.ui.semantics.semantics
 import androidx.compose.ui.text.TextStyle
 import androidx.compose.ui.tooling.preview.Preview
 import androidx.compose.ui.unit.Dp
@@ -78,7 +83,24 @@ fun Tag(
     }
     val badgePadding = if (dismissible && type == TagType.INLINE) PaddingValues(top = 8.dp, end = 8.dp) else PaddingValues()
     val alphaModifier = if (enabled) modifier else modifier.alpha(0.5f)
-    Box(contentAlignment = Alignment.TopEnd, modifier = alphaModifier.padding(badgePadding)) {
+    val dismissText = stringResource(R.string.tag_dismiss)
+
+    Box(
+        contentAlignment = Alignment.TopEnd,
+        modifier = alphaModifier
+            .padding(badgePadding)
+            .semantics(mergeDescendants = true) {
+                if (!enabled) {
+                    disabled()
+                }
+                if (dismissible && enabled) {
+                    onClick(label = dismissText) {
+                        onDismiss()
+                        true
+                    }
+                }
+            }
+    ) {
         Box(
             modifier = Modifier
                 .background(
@@ -96,10 +118,13 @@ fun Tag(
                     Icon(
                         painter = painterResource(R.drawable.close),
                         tint = HorizonColors.Icon.default(),
-                        contentDescription = stringResource(R.string.tag_dismiss),
+                        contentDescription = null,
                         modifier = Modifier
                             .size(size.iconSize)
-                            .clickable { onDismiss() })
+                            .clickable(enabled = enabled) { onDismiss() }
+                            .clearAndSetSemantics { hideFromAccessibility() }
+                    )
+
                 }
             }
         }
@@ -107,7 +132,7 @@ fun Tag(
             Badge(
                 content = BadgeContent.Icon(
                     iconRes = R.drawable.close_small,
-                    contentDescription = stringResource(R.string.tag_dismiss)
+                    contentDescription = null
                 ),
                 modifier = Modifier.offset(x = 8.dp, y = (-8).dp)
             )
diff --git a/libs/horizon/src/main/java/com/instructure/horizon/horizonui/molecules/filedrop/FileDrop.kt b/libs/horizon/src/main/java/com/instructure/horizon/horizonui/molecules/filedrop/FileDrop.kt
index 6a97064a04..fe7616f5b2 100644
--- a/libs/horizon/src/main/java/com/instructure/horizon/horizonui/molecules/filedrop/FileDrop.kt
+++ b/libs/horizon/src/main/java/com/instructure/horizon/horizonui/molecules/filedrop/FileDrop.kt
@@ -118,6 +118,7 @@ fun FileDrop(
 sealed class FileDropItemState(
     open val fileName: String,
     open val actionIconRes: Int,
+    open val actionIconContentDescriptionRes: Int,
     open val onActionClick: (() -> Unit)? = null,
     open val onClick: (() -> Unit)? = null
 ) {
@@ -125,34 +126,38 @@ sealed class FileDropItemState(
         override val fileName: String,
         override val onActionClick: (() -> Unit)? = null,
         override val onClick: (() -> Unit)? = null,
-        override val actionIconRes: Int = R.drawable.delete
+        override val actionIconRes: Int = R.drawable.delete,
+        override val actionIconContentDescriptionRes: Int = R.string.a11y_delete
     ) :
-        FileDropItemState(fileName, actionIconRes)
+        FileDropItemState(fileName, actionIconRes, actionIconContentDescriptionRes)
 
     data class InProgress(
         override val fileName: String,
         val progress: Float? = null,
         override val onActionClick: (() -> Unit)? = null,
         override val onClick: (() -> Unit)? = null,
-        override val actionIconRes: Int = R.drawable.close
+        override val actionIconRes: Int = R.drawable.close,
+        override val actionIconContentDescriptionRes: Int = R.string.a11y_cancel
     ) :
-        FileDropItemState(fileName, actionIconRes)
+        FileDropItemState(fileName, actionIconRes, actionIconContentDescriptionRes)
 
     data class NoLongerEditable(
         override val fileName: String,
         override val onActionClick: (() -> Unit)? = null,
         override val onClick: (() -> Unit)? = null,
-        override val actionIconRes: Int = R.drawable.download
+        override val actionIconRes: Int = R.drawable.download,
+        override val actionIconContentDescriptionRes: Int = R.string.a11y_download
     ) :
-        FileDropItemState(fileName, actionIconRes)
+        FileDropItemState(fileName, actionIconRes, actionIconContentDescriptionRes)
 
     data class Error(
         override val fileName: String,
         override val onActionClick: (() -> Unit)? = null,
         override val onClick: (() -> Unit)? = null,
-        override val actionIconRes: Int = R.drawable.refresh
+        override val actionIconRes: Int = R.drawable.refresh,
+        override val actionIconContentDescriptionRes: Int = R.string.a11y_retry
     ) :
-        FileDropItemState(fileName, actionIconRes)
+        FileDropItemState(fileName, actionIconRes, actionIconContentDescriptionRes)
 
 }
 
@@ -217,6 +222,7 @@ fun FileDropItem(
             state.onActionClick?.let {
                 IconButton(
                     iconRes = state.actionIconRes,
+                    contentDescription = stringResource(state.actionIconContentDescriptionRes),
                     size = IconButtonSize.SMALL,
                     color = IconButtonColor.Inverse,
                     onClick = it
diff --git a/libs/horizon/src/main/java/com/instructure/horizon/horizonui/organisms/controls/CheckboxItem.kt b/libs/horizon/src/main/java/com/instructure/horizon/horizonui/organisms/controls/CheckboxItem.kt
index 0d49645fcd..22d5e16214 100644
--- a/libs/horizon/src/main/java/com/instructure/horizon/horizonui/organisms/controls/CheckboxItem.kt
+++ b/libs/horizon/src/main/java/com/instructure/horizon/horizonui/organisms/controls/CheckboxItem.kt
@@ -17,12 +17,15 @@ package com.instructure.horizon.horizonui.organisms.controls
 
 import androidx.compose.foundation.layout.Row
 import androidx.compose.foundation.layout.size
+import androidx.compose.foundation.selection.toggleable
+import androidx.compose.foundation.selection.triStateToggleable
 import androidx.compose.material3.Checkbox
 import androidx.compose.material3.CheckboxColors
 import androidx.compose.material3.TriStateCheckbox
 import androidx.compose.runtime.Composable
 import androidx.compose.ui.Modifier
 import androidx.compose.ui.draw.alpha
+import androidx.compose.ui.semantics.clearAndSetSemantics
 import androidx.compose.ui.state.ToggleableState
 import androidx.compose.ui.tooling.preview.Preview
 import androidx.compose.ui.unit.dp
@@ -47,14 +50,24 @@ data class CheckboxItemState(
 @Composable
 fun TriStateCheckboxItem(state: TriStateCheckboxItemState, modifier: Modifier = Modifier) {
     val alphaModifier = if (state.enabled) modifier else modifier.alpha(0.5f)
-    Row(modifier = alphaModifier) {
+
+    Row(
+        modifier = alphaModifier
+            .triStateToggleable(
+                state = state.toggleableState,
+                onClick = state.onClick ?: {},
+                enabled = state.enabled
+            )
+    ) {
         val error = state.controlsContentState.error != null
         TriStateCheckbox(
             state = state.toggleableState,
-            onClick = state.onClick,
+            onClick = {},
             enabled = state.enabled,
             colors = horizonCheckboxColors(error),
-            modifier = Modifier.size(20.dp)
+            modifier = Modifier
+                .size(20.dp)
+                .clearAndSetSemantics {}
         )
         HorizonSpace(SpaceSize.SPACE_8)
         ControlsContent(state = state.controlsContentState)
@@ -64,14 +77,24 @@ fun TriStateCheckboxItem(state: TriStateCheckboxItemState, modifier: Modifier =
 @Composable
 fun CheckboxItem(state: CheckboxItemState, modifier: Modifier = Modifier) {
     val alphaModifier = if (state.enabled) modifier else modifier.alpha(0.5f)
-    Row(modifier = alphaModifier) {
+
+    Row(
+        modifier = alphaModifier
+            .toggleable(
+                value = state.checked,
+                onValueChange = state.onCheckedChanged ?: {},
+                enabled = state.enabled
+            )
+    ) {
         val error = state.controlsContentState.error != null
         Checkbox(
             checked = state.checked,
-            onCheckedChange = state.onCheckedChanged,
+            onCheckedChange = null,
             enabled = state.enabled,
             colors = horizonCheckboxColors(error),
-            modifier = Modifier.size(20.dp)
+            modifier = Modifier
+                .size(20.dp)
+                .clearAndSetSemantics {}
         )
         HorizonSpace(SpaceSize.SPACE_8)
         ControlsContent(state = state.controlsContentState)
diff --git a/libs/horizon/src/main/java/com/instructure/horizon/horizonui/organisms/inputs/common/InputDropDownPopup.kt b/libs/horizon/src/main/java/com/instructure/horizon/horizonui/organisms/inputs/common/InputDropDownPopup.kt
index f0fe2e226e..faf3b850e3 100644
--- a/libs/horizon/src/main/java/com/instructure/horizon/horizonui/organisms/inputs/common/InputDropDownPopup.kt
+++ b/libs/horizon/src/main/java/com/instructure/horizon/horizonui/organisms/inputs/common/InputDropDownPopup.kt
@@ -18,6 +18,7 @@ package com.instructure.horizon.horizonui.organisms.inputs.common
 
 import androidx.compose.animation.AnimatedContent
 import androidx.compose.animation.AnimatedVisibility
+import androidx.compose.animation.core.MutableTransitionState
 import androidx.compose.animation.expandVertically
 import androidx.compose.animation.shrinkVertically
 import androidx.compose.animation.togetherWith
@@ -35,14 +36,19 @@ import androidx.compose.material3.Card
 import androidx.compose.material3.CardDefaults
 import androidx.compose.material3.Text
 import androidx.compose.runtime.Composable
+import androidx.compose.runtime.LaunchedEffect
+import androidx.compose.runtime.remember
 import androidx.compose.ui.Alignment
 import androidx.compose.ui.Modifier
+import androidx.compose.ui.platform.LocalContext
 import androidx.compose.ui.res.stringResource
 import androidx.compose.ui.unit.Dp
 import androidx.compose.ui.unit.IntOffset
 import androidx.compose.ui.unit.dp
 import androidx.compose.ui.window.Popup
 import androidx.compose.ui.window.PopupProperties
+import android.content.Context
+import android.view.accessibility.AccessibilityManager
 import com.instructure.horizon.R
 import com.instructure.horizon.horizonui.foundation.HorizonColors
 import com.instructure.horizon.horizonui.foundation.HorizonCornerRadius
@@ -70,85 +76,101 @@ fun <T> InputDropDownPopup(
         SingleSelectItem(selectionOption.toString())
     },
 ) {
-    Popup(
-        alignment = Alignment.TopStart,
-        offset = IntOffset(
-            -SpaceSize.SPACE_8.value.toPx,
-            verticalOffsetPx + SpaceSize.SPACE_8.value.toPx
-        ),
-        onDismissRequest = { onMenuOpenChanged(false) },
-        properties = PopupProperties(focusable = isMenuOpen && isFocusable)
-    ) {
-        AnimatedVisibility(
-            isMenuOpen,
-            enter = expandVertically(expandFrom = Alignment.Top),
-            exit = shrinkVertically(shrinkTowards = Alignment.Top),
-            label = "InputDropDownPopupAnimation",
+    val visibleState = remember { MutableTransitionState(isMenuOpen) }
+
+    LaunchedEffect(isMenuOpen) {
+        visibleState.targetState = isMenuOpen
+    }
+
+    val context = LocalContext.current
+    val accessibilityManager = remember {
+        context.getSystemService(Context.ACCESSIBILITY_SERVICE) as AccessibilityManager
+    }
+    val isTalkBackEnabled = accessibilityManager.isEnabled && accessibilityManager.isTouchExplorationEnabled
+
+    if (!visibleState.isIdle || visibleState.currentState) {
+        Popup(
+            alignment = Alignment.TopStart,
+            offset = IntOffset(
+                -SpaceSize.SPACE_8.value.toPx,
+                verticalOffsetPx + SpaceSize.SPACE_8.value.toPx
+            ),
+            onDismissRequest = { onMenuOpenChanged(false) },
+            properties = PopupProperties(
+                focusable = visibleState.targetState && (isFocusable || isTalkBackEnabled)
+            )
         ) {
-            Card(
-                modifier = modifier
-                    .padding(bottom = 8.dp)
-                    .padding(horizontal = 8.dp)
-                    .conditional(width == null) {
-                        fillMaxWidth()
-                    }
-                    .conditional(width != null) {
-                        width(width!!)
-                    },
-                shape = HorizonCornerRadius.level2,
-                colors = CardDefaults.cardColors()
-                    .copy(containerColor = HorizonColors.Surface.pageSecondary()),
-                border = if (isMenuOpen) {
-                    BorderStroke(
-                        width = 1.dp,
-                        color = HorizonColors.LineAndBorder.containerStroke()
-                    )
-                } else {
-                    null
-                },
+            AnimatedVisibility(
+                visibleState = visibleState,
+                enter = expandVertically(expandFrom = Alignment.Top),
+                exit = shrinkVertically(shrinkTowards = Alignment.Top),
+                label = "InputDropDownPopupAnimation",
             ) {
-                AnimatedContent(
-                    isLoading,
-                    transitionSpec = { expandVertically() togetherWith shrinkVertically() }
-                ) { isLoading ->
-                    Column(
-                        modifier = Modifier
-                            .verticalScroll(rememberScrollState())
-                    ) {
-                        if (isLoading) {
-                            Row(
-                                verticalAlignment = Alignment.CenterVertically,
-                                horizontalArrangement = Arrangement.Center,
-                                modifier = Modifier
-                                    .fillMaxWidth()
-                                    .padding(16.dp)
-                            ) {
-                                Spinner(size = SpinnerSize.EXTRA_SMALL)
-                            }
-                        } else if (options.isEmpty()) {
-                            Row(
-                                verticalAlignment = Alignment.CenterVertically,
-                                modifier = Modifier
-                                    .fillMaxWidth()
-                            ) {
-                                SingleSelectItem(stringResource(R.string.noOptionsAvailable))
-                            }
-                        } else {
-                            options.forEach { selectionOption ->
+                Card(
+                    modifier = modifier
+                        .padding(bottom = 8.dp)
+                        .padding(horizontal = 8.dp)
+                        .conditional(width == null) {
+                            fillMaxWidth()
+                        }
+                        .conditional(width != null) {
+                            width(width!!)
+                        },
+                    shape = HorizonCornerRadius.level2,
+                    colors = CardDefaults.cardColors()
+                        .copy(containerColor = HorizonColors.Surface.pageSecondary()),
+                    border = if (visibleState.targetState) {
+                        BorderStroke(
+                            width = 1.dp,
+                            color = HorizonColors.LineAndBorder.containerStroke()
+                        )
+                    } else {
+                        null
+                    },
+                ) {
+                    AnimatedContent(
+                        isLoading,
+                        transitionSpec = { expandVertically() togetherWith shrinkVertically() }
+                    ) { isLoading ->
+                        Column(
+                            modifier = Modifier
+                                .verticalScroll(rememberScrollState())
+                        ) {
+                            if (isLoading) {
+                                Row(
+                                    verticalAlignment = Alignment.CenterVertically,
+                                    horizontalArrangement = Arrangement.Center,
+                                    modifier = Modifier
+                                        .fillMaxWidth()
+                                        .padding(16.dp)
+                                ) {
+                                    Spinner(size = SpinnerSize.EXTRA_SMALL)
+                                }
+                            } else if (options.isEmpty()) {
                                 Row(
                                     verticalAlignment = Alignment.CenterVertically,
                                     modifier = Modifier
                                         .fillMaxWidth()
-                                        .conditional(optionEnabled(selectionOption)) {
-                                            clickable {
-                                                onOptionSelected(selectionOption)
-                                                if (closeMenuAfterSelection(selectionOption)) {
-                                                    onMenuOpenChanged(false)
+                                ) {
+                                    SingleSelectItem(stringResource(R.string.noOptionsAvailable))
+                                }
+                            } else {
+                                options.forEach { selectionOption ->
+                                    Row(
+                                        verticalAlignment = Alignment.CenterVertically,
+                                        modifier = Modifier
+                                            .fillMaxWidth()
+                                            .conditional(optionEnabled(selectionOption)) {
+                                                clickable {
+                                                    onOptionSelected(selectionOption)
+                                                    if (closeMenuAfterSelection(selectionOption)) {
+                                                        onMenuOpenChanged(false)
+                                                    }
                                                 }
                                             }
-                                        }
-                                ) {
-                                    item(selectionOption)
+                                    ) {
+                                        item(selectionOption)
+                                    }
                                 }
                             }
                         }
diff --git a/libs/horizon/src/main/java/com/instructure/horizon/horizonui/organisms/inputs/multiselect/MultiSelect.kt b/libs/horizon/src/main/java/com/instructure/horizon/horizonui/organisms/inputs/multiselect/MultiSelect.kt
index 289d8694f1..9705d139c5 100644
--- a/libs/horizon/src/main/java/com/instructure/horizon/horizonui/organisms/inputs/multiselect/MultiSelect.kt
+++ b/libs/horizon/src/main/java/com/instructure/horizon/horizonui/organisms/inputs/multiselect/MultiSelect.kt
@@ -40,6 +40,12 @@ import androidx.compose.ui.layout.onGloballyPositioned
 import androidx.compose.ui.platform.LocalContext
 import androidx.compose.ui.platform.LocalDensity
 import androidx.compose.ui.res.painterResource
+import androidx.compose.ui.res.stringResource
+import androidx.compose.ui.semantics.Role
+import androidx.compose.ui.semantics.contentDescription
+import androidx.compose.ui.semantics.role
+import androidx.compose.ui.semantics.semantics
+import androidx.compose.ui.semantics.stateDescription
 import androidx.compose.ui.tooling.preview.Preview
 import androidx.compose.ui.unit.dp
 import com.instructure.canvasapi2.utils.ContextKeeper
@@ -58,6 +64,9 @@ fun MultiSelect(
     state: MultiSelectState,
     modifier: Modifier = Modifier
 ) {
+    val expandedState = stringResource(R.string.a11y_expanded)
+    val collapsedState = stringResource(R.string.a11y_collapsed)
+
     Input(
         label = state.label,
         helperText = state.helperText,
@@ -70,6 +79,15 @@ fun MultiSelect(
     ) {
         Column(
             modifier = Modifier
+                .semantics(mergeDescendants = false) {
+                    role = Role.DropdownList
+                    stateDescription = if (state.isMenuOpen) expandedState else collapsedState
+                    contentDescription = if (state.selectedOptions.isEmpty()) {
+                        state.label ?: ""
+                    } else {
+                        "${state.label}, ${state.selectedOptions.size} items selected"
+                    }
+                }
         ) {
             val localDensity = LocalDensity.current
             var heightInPx by remember { mutableIntStateOf(0) }
@@ -141,6 +159,7 @@ private fun MultiSelectContent(state: MultiSelectState) {
                             MultiSelectInputSize.Small -> TagSize.SMALL
                             MultiSelectInputSize.Medium -> TagSize.MEDIUM
                         },
+                        enabled = state.enabled,
                         dismissible = true,
                         onDismiss = {
                             state.onOptionRemoved(selectedOption)
diff --git a/libs/horizon/src/main/java/com/instructure/horizon/horizonui/organisms/inputs/multiselectsearch/MultiSelectSearch.kt b/libs/horizon/src/main/java/com/instructure/horizon/horizonui/organisms/inputs/multiselectsearch/MultiSelectSearch.kt
index 13da75ef2a..cd4cd4a83a 100644
--- a/libs/horizon/src/main/java/com/instructure/horizon/horizonui/organisms/inputs/multiselectsearch/MultiSelectSearch.kt
+++ b/libs/horizon/src/main/java/com/instructure/horizon/horizonui/organisms/inputs/multiselectsearch/MultiSelectSearch.kt
@@ -175,6 +175,7 @@ private fun MultiSelectContent(state: MultiSelectSearchState) {
                             MultiSelectSearchInputSize.Small -> TagSize.SMALL
                             MultiSelectSearchInputSize.Medium -> TagSize.MEDIUM
                         },
+                        enabled = state.enabled,
                         dismissible = true,
                         onDismiss = {
                             state.onOptionRemoved(selectedOption)
diff --git a/libs/horizon/src/main/java/com/instructure/horizon/horizonui/organisms/inputs/singleselect/SingleSelect.kt b/libs/horizon/src/main/java/com/instructure/horizon/horizonui/organisms/inputs/singleselect/SingleSelect.kt
index 1f606993e2..82be340a4c 100644
--- a/libs/horizon/src/main/java/com/instructure/horizon/horizonui/organisms/inputs/singleselect/SingleSelect.kt
+++ b/libs/horizon/src/main/java/com/instructure/horizon/horizonui/organisms/inputs/singleselect/SingleSelect.kt
@@ -76,9 +76,9 @@ fun SingleSelect(
                 role = Role.DropdownList
                 stateDescription = if (state.isMenuOpen) expandedState else collapsedState
                 contentDescription = if (state.selectedOption != null) {
-                    "${state.label}, ${state.selectedOption}"
+                    "${state.label ?: state.placeHolderText ?: ""}, ${state.selectedOption}"
                 } else {
-                    state.label ?: ""
+                    state.label ?: state.placeHolderText ?: ""
                 }
             }
     ) {
diff --git a/libs/horizon/src/main/java/com/instructure/horizon/horizonui/organisms/inputs/singleselectimage/SingleSelectImage.kt b/libs/horizon/src/main/java/com/instructure/horizon/horizonui/organisms/inputs/singleselectimage/SingleSelectImage.kt
index fe9e9d8b15..9cd97264a5 100644
--- a/libs/horizon/src/main/java/com/instructure/horizon/horizonui/organisms/inputs/singleselectimage/SingleSelectImage.kt
+++ b/libs/horizon/src/main/java/com/instructure/horizon/horizonui/organisms/inputs/singleselectimage/SingleSelectImage.kt
@@ -42,6 +42,12 @@ import androidx.compose.ui.layout.onGloballyPositioned
 import androidx.compose.ui.platform.LocalContext
 import androidx.compose.ui.platform.LocalDensity
 import androidx.compose.ui.res.painterResource
+import androidx.compose.ui.res.stringResource
+import androidx.compose.ui.semantics.Role
+import androidx.compose.ui.semantics.clearAndSetSemantics
+import androidx.compose.ui.semantics.contentDescription
+import androidx.compose.ui.semantics.role
+import androidx.compose.ui.semantics.stateDescription
 import androidx.compose.ui.tooling.preview.Preview
 import androidx.compose.ui.unit.dp
 import androidx.core.graphics.drawable.toBitmap
@@ -58,7 +64,8 @@ fun SingleSelectImage(
     state: SingleSelectImageState,
     modifier: Modifier = Modifier
 ) {
-
+    val expandedState = stringResource(R.string.a11y_expanded)
+    val collapsedState = stringResource(R.string.a11y_collapsed)
     Input(
         label = state.label,
         helperText = state.helperText,
@@ -68,6 +75,15 @@ fun SingleSelectImage(
             .onFocusChanged {
                 state.onFocusChanged(it.isFocused)
             }
+            .clearAndSetSemantics {
+                role = Role.DropdownList
+                stateDescription = if (state.isMenuOpen) expandedState else collapsedState
+                contentDescription = if (state.selectedOption != null) {
+                    "${state.label}, ${state.selectedOption}"
+                } else {
+                    state.label ?: ""
+                }
+            }
     ) {
         Column(
             modifier = Modifier
diff --git a/libs/horizon/src/main/res/values/strings.xml b/libs/horizon/src/main/res/values/strings.xml
index b1d91ae53c..e205605507 100644
--- a/libs/horizon/src/main/res/values/strings.xml
+++ b/libs/horizon/src/main/res/values/strings.xml
@@ -479,6 +479,12 @@
     <string name="editNoteExitConfirmationExitButtonLabel">Exit</string>
     <string name="editNoteExitConfirmationCancelButtonLabel">Cancel</string>
     <string name="a11y_notebookDeleteNoteButtonContentDescription">Delete note</string>
+    <string name="a11y_delete">Delete</string>
+    <string name="a11y_cancel">Cancel</string>
+    <string name="a11y_download">Download</string>
+    <string name="a11y_retry">Retry</string>
+    <string name="a11y_readInboxMessage">Read</string>
+    <string name="a11y_unreadInboxMessage">Unread</string>
     <string name="a11y_previousModuleItem">Previous module item</string>
     <string name="a11y_openAIAssistant">Open AI Assistant</string>
     <string name="a11y_openNotebook">Open notebook</string>