diff --git a/lightdash/client.py b/lightdash/client.py
index 2e44768..09d65a2 100644
--- a/lightdash/client.py
+++ b/lightdash/client.py
@@ -33,6 +33,7 @@ def __init__(self, instance_url: str, access_token: str, project_uuid: str, conf
         self.instance_url = instance_url.rstrip('/')
         self.access_token = access_token
         self.project_uuid = project_uuid
+        self.auth_header = "Bearer" if access_token.startswith("ldsvc_") else "ApiKey"
         
         # Extract config values with defaults
         config = config or {}
@@ -88,7 +89,7 @@ def _make_request(
         
         with httpx.Client(
             headers={
-                "Authorization": f"ApiKey {self.access_token}",
+                "Authorization": f"{self.auth_header} {self.access_token}",
                 "Accept": "application/json",
             },
             timeout=self.timeout