diff --git a/roboflow/adapters/rfapi.py b/roboflow/adapters/rfapi.py
index e29b2b2e..528932c6 100644
--- a/roboflow/adapters/rfapi.py
+++ b/roboflow/adapters/rfapi.py
@@ -780,6 +780,7 @@ def save_annotation(
     is_prediction: bool = False,
     annotation_labelmap=None,
     overwrite: bool = False,
+    add_to_dataset: Optional[bool] = None,
 ):
     """
     Upload an annotation to a specific project.
@@ -787,10 +788,22 @@ def save_annotation(
     Args:
         annotation_path (str): path to annotation you'd like to upload
         image_id (str): image id you'd like to upload that has annotations for it.
+        add_to_dataset (bool | None): whether the annotated image joins the project's Dataset,
+            and so the next dataset version. `None` (the default) leaves the choice to the API,
+            which adds the image. Pass `False` to store the annotation without changing Dataset
+            membership — for example while the image is still waiting to be labeled or reviewed
+            in a batch. Prediction uploads never add the image to the Dataset.
     """
 
     upload_url = _save_annotation_url(
-        api_key, project_url, annotation_name, image_id, job_name, is_prediction, overwrite
+        api_key,
+        project_url,
+        annotation_name,
+        image_id,
+        job_name,
+        is_prediction,
+        overwrite,
+        add_to_dataset,
     )
 
     try:
@@ -829,7 +842,9 @@ def save_annotation(
     return responsejson
 
 
-def _save_annotation_url(api_key, project_url, name, image_id, job_name, is_prediction, overwrite=False):
+def _save_annotation_url(
+    api_key, project_url, name, image_id, job_name, is_prediction, overwrite=False, add_to_dataset=None
+):
     url = f"{API_URL}/dataset/{project_url}/annotate/{image_id}?api_key={api_key}&name={name}"
     if job_name:
         url += f"&jobName={job_name}"
@@ -837,6 +852,9 @@ def _save_annotation_url(api_key, project_url, name, image_id, job_name, is_pred
         url += "&prediction=true"
     if overwrite:
         url += "&overwrite=true"
+    # Omitted means "whatever the API does by default", which today is to add the image.
+    if add_to_dataset is not None:
+        url += f"&addToDataset={'true' if add_to_dataset else 'false'}"
     return url
 
 
diff --git a/roboflow/core/project.py b/roboflow/core/project.py
index f9fe8fb5..03dc0ab6 100644
--- a/roboflow/core/project.py
+++ b/roboflow/core/project.py
@@ -553,7 +553,18 @@ def save_annotation(
         is_prediction: bool = False,
         annotation_overwrite=False,
         num_retry_uploads=0,
+        add_to_dataset: Optional[bool] = None,
     ):
+        """
+        Upload an annotation for an image that is already in the project.
+
+        Args:
+            add_to_dataset (bool | None): whether the annotated image joins the project's
+                Dataset, and so the next dataset version. `None` (the default) leaves the
+                choice to the API, which adds the image. Pass `False` to store the annotation
+                without changing Dataset membership — for example while the image is still
+                waiting to be labeled or reviewed in a batch.
+        """
         project_url = self.id.rsplit("/")[1]
         annotation_name, annotation_str = self._annotation_params(annotation_path)
         t0 = time.time()
@@ -571,6 +582,7 @@ def save_annotation(
                 is_prediction=is_prediction,
                 annotation_labelmap=annotation_labelmap,
                 overwrite=annotation_overwrite,
+                add_to_dataset=add_to_dataset,
             )
             upload_retry_attempts = retry.retries
         except AnnotationSaveError as e:
@@ -597,6 +609,7 @@ def single_upload(
         sequence_number=None,
         sequence_size=None,
         metadata: Optional[Dict] = None,
+        add_to_dataset: Optional[bool] = None,
         **kwargs,
     ):
         if tag_names is None:
@@ -637,6 +650,7 @@ def single_upload(
                 is_prediction,
                 annotation_overwrite,
                 num_retry_uploads=num_retry_uploads,
+                add_to_dataset=add_to_dataset,
             )
 
         return {
diff --git a/tests/test_rfapi.py b/tests/test_rfapi.py
index d0106312..44542740 100644
--- a/tests/test_rfapi.py
+++ b/tests/test_rfapi.py
@@ -8,6 +8,7 @@
 
 from roboflow.adapters.rfapi import (
     RoboflowError,
+    _save_annotation_url,
     create_training_v2,
     delete_version_training,
     get_train_recipe,
@@ -434,3 +435,45 @@ def test_restore_trash_item_restores_a_training(self):
 
 if __name__ == "__main__":
     unittest.main()
+
+
+class TestSaveAnnotationUrl(unittest.TestCase):
+    API_KEY = "test_api_key"
+    PROJECT_URL = "test_project"
+    IMAGE_ID = "test_image_id"
+    ANNOTATION_NAME = "annotation.json"
+
+    def _url(self, **kwargs):
+        return _save_annotation_url(
+            self.API_KEY,
+            self.PROJECT_URL,
+            self.ANNOTATION_NAME,
+            self.IMAGE_ID,
+            kwargs.pop("job_name", None),
+            kwargs.pop("is_prediction", False),
+            **kwargs,
+        )
+
+    def test_add_to_dataset_is_omitted_by_default(self):
+        # Omitting the parameter leaves the choice to the API, which adds the image to the
+        # Dataset. Sending it unasked would silently change what existing callers upload.
+        self.assertNotIn("addToDataset", self._url())
+
+    def test_add_to_dataset_false_opts_out(self):
+        self.assertIn("addToDataset=false", self._url(add_to_dataset=False))
+
+    def test_add_to_dataset_true_is_explicit(self):
+        self.assertIn("addToDataset=true", self._url(add_to_dataset=True))
+
+    def test_add_to_dataset_composes_with_the_other_parameters(self):
+        url = self._url(
+            job_name="my-job",
+            is_prediction=True,
+            overwrite=True,
+            add_to_dataset=False,
+        )
+
+        self.assertIn("jobName=my-job", url)
+        self.assertIn("prediction=true", url)
+        self.assertIn("overwrite=true", url)
+        self.assertIn("addToDataset=false", url)