diff --git a/src/eva/language/models/wrappers/base.py b/src/eva/language/models/wrappers/base.py
index 548586255..bb9580b1c 100644
--- a/src/eva/language/models/wrappers/base.py
+++ b/src/eva/language/models/wrappers/base.py
@@ -21,19 +21,31 @@ class LanguageModel(base.BaseModel[TextBatch, List[str]]):
         expected by the `model_forward` method.
     """
 
+    _default_system_prompt = (
+        "You are a helpful language assistant. "
+        "You are able to process the text content that the user provides,"
+        "and assist the user with a variety of tasks using natural language."
+    )
+
     def __init__(
-        self, system_prompt: str | None, output_transforms: Callable | None = None
+        self, system_prompt: str | None = None, output_transforms: Callable | None = None
     ) -> None:
         """Creates a new model instance.
 
         Args:
-            system_prompt: The system prompt to use for the model (optional).
+            system_prompt: The system prompt to use for the model. If set to None,
+                will use the default system prompt. If you don't want to use any
+                system prompt, you can set this to an empty string.
             output_transforms: Optional transforms to apply to the output of
                 the model's forward pass.
         """
         super().__init__(transforms=output_transforms)
 
-        self.system_message = ModelSystemMessage(content=system_prompt) if system_prompt else None
+        self.system_message = (
+            ModelSystemMessage(content=system_prompt or self._default_system_prompt)
+            if system_prompt != ""
+            else None
+        )
 
     @override
     def forward(self, batch: TextBatch) -> List[str]:
diff --git a/src/eva/multimodal/models/wrappers/base.py b/src/eva/multimodal/models/wrappers/base.py
index 86bcd3d38..14e4ce617 100644
--- a/src/eva/multimodal/models/wrappers/base.py
+++ b/src/eva/multimodal/models/wrappers/base.py
@@ -21,19 +21,31 @@ class VisionLanguageModel(base.BaseModel[TextImageBatch, List[str]]):
         expected by the `model_forward` method.
     """
 
+    _default_system_prompt = (
+        "You are a helpful vision and language assistant. "
+        "You are able to understand the visual content that the user provides, "
+        "and assist the user with a variety of tasks using natural language."
+    )
+
     def __init__(
-        self, system_prompt: str | None, output_transforms: Callable | None = None
+        self, system_prompt: str | None = None, output_transforms: Callable | None = None
     ) -> None:
         """Creates a new model instance.
 
         Args:
-            system_prompt: The system prompt to use for the model (optional).
+            system_prompt: The system prompt to use for the model. If set to None,
+                will use the default system prompt. If you don't want to use any
+                system prompt, you can set this to an empty string.
             output_transforms: Optional transforms to apply to the output of
                 the model's forward pass.
         """
         super().__init__(transforms=output_transforms)
 
-        self.system_message = ModelSystemMessage(content=system_prompt) if system_prompt else None
+        self.system_message = (
+            ModelSystemMessage(content=system_prompt or self._default_system_prompt)
+            if system_prompt != ""
+            else None
+        )
 
     @override
     def forward(self, batch: TextImageBatch) -> List[str]: