diff --git a/src/browser/tsconfig.json b/src/browser/tsconfig.json
index 62737ee..90aca08 100644
--- a/src/browser/tsconfig.json
+++ b/src/browser/tsconfig.json
@@ -1,6 +1,6 @@
 {
   "compilerOptions": {
-    "lib": ["es5", "es2015.collection", "dom"],
+    "lib": ["es2017", "dom"],
     "types": [],
     "module": "esnext",
     "moduleResolution": "node",
diff --git a/src/build/index.ts b/src/build/index.ts
index e783cd0..758847a 100644
--- a/src/build/index.ts
+++ b/src/build/index.ts
@@ -13,4 +13,9 @@ export {
   Value,
   resolveTheme,
   resolveThemeWithPaths,
+  ReferenceTokens,
+  ColorReferenceTokens,
+  ColorPaletteInput,
+  ColorPaletteDefinition,
+  PaletteStep,
 } from '../shared/theme';
diff --git a/src/shared/theme/__tests__/builder.test.ts b/src/shared/theme/__tests__/builder.test.ts
index 7081672..116e222 100644
--- a/src/shared/theme/__tests__/builder.test.ts
+++ b/src/shared/theme/__tests__/builder.test.ts
@@ -55,3 +55,26 @@ test('theme adds context', () => {
     },
   });
 });
+
+test('theme adds reference tokens', () => {
+  builder.addReferenceTokens({
+    color: {
+      neutral: { 900: '#242E3C' },
+      warning: { 400: '#ff9900' },
+    },
+  });
+
+  const theme = builder.build();
+
+  expect(theme.referenceTokens).toMatchObject({
+    color: {
+      neutral: { 900: '#242E3C' },
+      warning: { 400: '#ff9900' },
+    },
+  });
+
+  expect(theme.tokens).toMatchObject({
+    colorNeutral900: '#242E3C',
+    colorWarning400: '#ff9900',
+  });
+});
diff --git a/src/shared/theme/builder.ts b/src/shared/theme/builder.ts
index c054ca6..4baccfb 100644
--- a/src/shared/theme/builder.ts
+++ b/src/shared/theme/builder.ts
@@ -1,6 +1,15 @@
 // Copyright Amazon.com, Inc. or its affiliates. All Rights Reserved.
 // SPDX-License-Identifier: Apache-2.0
-import { Theme, Context, Mode } from './interfaces';
+import {
+  Theme,
+  Context,
+  Mode,
+  ReferenceTokens,
+  ColorReferenceTokens,
+  ColorPaletteInput,
+  PaletteStep,
+  ColorPaletteDefinition,
+} from './interfaces';
 
 export type TokenCategory<T extends string, V> = Record<T, V>;
 
@@ -46,7 +55,60 @@ export class ThemeBuilder {
     return this;
   }
 
+  addReferenceTokens(referenceTokens: ReferenceTokens): ThemeBuilder {
+    this.theme.referenceTokens = referenceTokens;
+
+    // Process reference tokens and add generated tokens to theme
+    if (referenceTokens.color) {
+      const generatedTokens = this.processReferenceTokens(referenceTokens.color);
+      this.theme.tokens = { ...this.theme.tokens, ...generatedTokens };
+    }
+
+    return this;
+  }
+
   build(): Theme {
     return this.theme;
   }
+
+  private processReferenceTokens(colorTokens: ColorReferenceTokens): TokenCategory<string, string> {
+    const generatedTokens: TokenCategory<string, string> = {};
+
+    Object.entries(colorTokens).forEach(([colorName, paletteInput]) => {
+      const palette = this.processColorPaletteInput(paletteInput);
+
+      // Add generated palette tokens with naming convention: colorPrimary50, colorPrimary600, etc.
+      Object.entries(palette).forEach(([step, value]) => {
+        const tokenName = `color${this.capitalize(colorName)}${step}`;
+        generatedTokens[tokenName] = value;
+      });
+    });
+
+    return generatedTokens;
+  }
+
+  // Right now just validates steps, but will also handle seed token color generation in a future PR
+  private processColorPaletteInput(input: ColorPaletteInput): ColorPaletteDefinition {
+    const validSteps: number[] = [];
+    // Add steps 50-1000 in increments of 50
+    for (let i = 50; i <= 1000; i += 50) {
+      validSteps.push(i);
+    }
+
+    const result: ColorPaletteDefinition = {};
+
+    // Add explicit step values
+    Object.entries(input).forEach(([step, value]) => {
+      const numStep = Number(step);
+      if (value && validSteps.includes(numStep)) {
+        result[numStep as PaletteStep] = value;
+      }
+    });
+
+    return result;
+  }
+
+  private capitalize(str: string): string {
+    return str.charAt(0).toUpperCase() + str.slice(1);
+  }
 }
diff --git a/src/shared/theme/index.ts b/src/shared/theme/index.ts
index 92a14a0..4c71d4d 100644
--- a/src/shared/theme/index.ts
+++ b/src/shared/theme/index.ts
@@ -11,6 +11,11 @@ export {
   GlobalValue,
   ModeValue,
   TypedModeValueOverride,
+  ReferenceTokens,
+  ColorReferenceTokens,
+  ColorPaletteInput,
+  ColorPaletteDefinition,
+  PaletteStep,
 } from './interfaces';
 export { ThemeBuilder, TokenCategory } from './builder';
 export {
diff --git a/src/shared/theme/interfaces.ts b/src/shared/theme/interfaces.ts
index 6a93e88..0e5d101 100644
--- a/src/shared/theme/interfaces.ts
+++ b/src/shared/theme/interfaces.ts
@@ -35,8 +35,62 @@ export interface Theme {
   modes: Record<string, Mode>;
   tokenModeMap: Record<string, string>;
   contexts: Record<string, Context>;
+  referenceTokens?: ReferenceTokens;
 }
 
+/**
+ * Reference tokens enable seed-based palette generation and semantic token organization.
+ */
+export interface ReferenceTokens {
+  color?: ColorReferenceTokens;
+}
+
+export interface ColorReferenceTokens {
+  primary?: ColorPaletteInput;
+  neutral?: ColorPaletteInput;
+  error?: ColorPaletteInput;
+  success?: ColorPaletteInput;
+  warning?: ColorPaletteInput;
+  info?: ColorPaletteInput;
+}
+
+/**
+ * Color reference tokens organized by semantic color categories.
+ * Each category is defined as a palette definition with explicit color values.
+ */
+export type ColorPaletteInput = ColorPaletteDefinition;
+
+/**
+ * Palette steps available across all color types. Different color categories
+ * may use different subsets of these steps.
+ */
+export type PaletteStep =
+  | 50
+  | 100
+  | 150
+  | 200
+  | 250
+  | 300
+  | 350
+  | 400
+  | 450
+  | 500
+  | 550
+  | 600
+  | 650
+  | 700
+  | 750
+  | 800
+  | 850
+  | 900
+  | 950
+  | 1000;
+
+/**
+ * Color palette definition with explicit color values for palette steps.
+ */
+export type ColorPaletteDefinition = Partial<Record<PaletteStep, string>>;
+
 type Tokens = Partial<Record<string, GlobalValue | TypedModeValueOverride>>;
 
 export interface Override {