diff --git a/.changeset/inventive-tangible-hyena.md b/.changeset/inventive-tangible-hyena.md
new file mode 100644
index 00000000..cec9d424
--- /dev/null
+++ b/.changeset/inventive-tangible-hyena.md
@@ -0,0 +1,5 @@
+---
+"stagehand": patch
+---
+
+remove duplicate project id if already passed to Stagehand
diff --git a/stagehand/config.py b/stagehand/config.py
index 8805e40b..e69faa20 100644
--- a/stagehand/config.py
+++ b/stagehand/config.py
@@ -1,8 +1,8 @@
 import os
-from typing import Any, Callable, Literal, Optional
+from typing import Any, Callable, Literal, Optional, Union
 
 from browserbase.types import SessionCreateParams as BrowserbaseSessionCreateParams
-from pydantic import BaseModel, ConfigDict, Field
+from pydantic import BaseModel, ConfigDict, Field, field_validator
 
 from stagehand.schemas import AvailableModel
 
@@ -71,7 +71,9 @@ class StagehandConfig(BaseModel):
         alias="domSettleTimeoutMs",
         description="Timeout for DOM to settle (in ms)",
     )
-    browserbase_session_create_params: Optional[BrowserbaseSessionCreateParams] = Field(
+    browserbase_session_create_params: Optional[
+        Union[BrowserbaseSessionCreateParams, dict[str, Any]]
+    ] = Field(
         None,
         alias="browserbaseSessionCreateParams",
         description="Browserbase session create params",
@@ -118,6 +120,17 @@ class StagehandConfig(BaseModel):
 
     model_config = ConfigDict(populate_by_name=True)
 
+    @field_validator("browserbase_session_create_params", mode="before")
+    @classmethod
+    def validate_browserbase_params(cls, v, info):
+        """Validate and convert browserbase session create params."""
+        if isinstance(v, dict) and "project_id" not in v:
+            values = info.data
+            project_id = values.get("project_id") or values.get("projectId")
+            if project_id:
+                v = {**v, "project_id": project_id}
+        return v
+
     def with_overrides(self, **overrides) -> "StagehandConfig":
         """
         Create a new config instance with the specified overrides.