diff --git a/stagehand/config.py b/stagehand/config.py
index a577230..d9f4b9b 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
 
@@ -65,7 +65,7 @@ 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",
@@ -111,6 +111,17 @@ 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":
         """