diff --git a/nemo_gym/rollout_collection.py b/nemo_gym/rollout_collection.py
index f522d2b07..d03b8b237 100644
--- a/nemo_gym/rollout_collection.py
+++ b/nemo_gym/rollout_collection.py
@@ -51,7 +51,10 @@ class RolloutCollectionConfig(BaseNeMoGymCLIConfig):
     ```
     """
 
-    agent_name: str = Field(description="The agent to collect rollouts from.")
+    agent_name: Optional[str] = Field(
+        default=None,
+        description="The agent to collect rollouts from. If not specified, uses agent_ref from each data row.",
+    )
     input_jsonl_fpath: str = Field(
         description="The input data source to use to collect rollouts, in the form of a file path to a jsonl file."
     )
@@ -103,13 +106,23 @@ async def run_from_config(self, config: RolloutCollectionConfig):
         if config.responses_create_params:
             print(f"Overriding responses_create_params fields with {config.responses_create_params}")
 
+        # Validate all rows have an agent specified (either via config or agent_ref in data)
+        if not config.agent_name:
+            missing_agent_indices = [idx for idx, row in enumerate(rows) if not row.get("agent_ref", {}).get("name")]
+            if missing_agent_indices:
+                raise ValueError(
+                    f"No agent specified for rows {missing_agent_indices}. Either provide +agent_name config or include agent_ref in data."
+                )
+
         metrics = Counter()
         with open(config.output_jsonl_fpath, "a") as f:
 
             async def _post_coroutine(row: dict) -> None:
                 row["responses_create_params"] = row["responses_create_params"] | config.responses_create_params
+                # Use config.agent_name if specified, otherwise use agent_ref from the row
+                agent_name = config.agent_name or row.get("agent_ref", {}).get("name")
                 async with semaphore:
-                    response = await server_client.post(server_name=config.agent_name, url_path="/run", json=row)
+                    response = await server_client.post(server_name=agent_name, url_path="/run", json=row)
                     await raise_for_status(response)
                     result = await response.json()
                     f.write(json.dumps(result) + "\n")