diff --git a/docs/source/components/identifiers.md b/docs/source/components/identifiers.md
index b20bf0b68..b26cc6f62 100644
--- a/docs/source/components/identifiers.md
+++ b/docs/source/components/identifiers.md
@@ -11,6 +11,7 @@ Code or script identifier
 | `url` | `str` | Code URL (URL to code repository) |
 | `name` | `Optional[str]` | Name  |
 | `version` | `Optional[str]` | Code version  |
+| `commit_hash` | `Optional[str]` | Commit hash (Commit hash of the code.) |
 | `container` | Optional[[Container](#container)] | Container  |
 | `run_script` | `Optional[pathlib.Path]` | Run script (Path to run script) |
 | `language` | `Optional[str]` | Programming language (Programming language used) |
diff --git a/src/aind_data_schema/components/identifiers.py b/src/aind_data_schema/components/identifiers.py
index 5a3b2c3f8..428dc1fb5 100644
--- a/src/aind_data_schema/components/identifiers.py
+++ b/src/aind_data_schema/components/identifiers.py
@@ -5,8 +5,11 @@
 from typing import Dict, List, Optional
 
 from aind_data_schema_models.registries import Registry
-from pydantic import Field
+from pydantic import Field, model_validator
+import warnings
 
+from typing import Annotated
+from pydantic import StringConstraints
 from aind_data_schema.base import DataModel, DiscriminatedList, GenericModel
 
 
@@ -67,12 +70,22 @@ class Container(DataModel):
     uri: str = Field(..., title="URI", description="URI of the container, e.g. Docker Hub URL")
 
 
+CommitHash = Annotated[
+    str,
+    StringConstraints(
+        pattern=r"^[0-9a-fA-F]{7,60}$",
+        strip_whitespace=True,
+    ),
+]
+
+
 class Code(DataModel):
     """Code or script identifier"""
 
     url: str = Field(..., title="Code URL", description="URL to code repository")
     name: Optional[str] = Field(default=None, title="Name")
     version: Optional[str] = Field(default=None, title="Code version")
+    commit_hash: Optional[CommitHash] = Field(default=None, title="Commit hash", description="Commit hash of the code.")
 
     container: Optional[Container] = Field(default=None, title="Container")
     run_script: Optional[Path] = Field(default=None, title="Run script", description="Path to run script")
@@ -92,3 +105,14 @@ class Code(DataModel):
         title="Core dependency",
         description="For code with a core software package dependency, e.g. Bonsai",
     )
+
+    @model_validator(mode="after")
+    def _ensure_commit_hash_or_version(self) -> "Code":
+        """Ensure that at least one of commit_hash or version is provided for code identification"""
+        if not self.commit_hash and not self.version:
+            warnings.warn(
+                "Neither commit_hash nor version provided for Code. "
+                "It's recommended to provide at least one to ensure reproducibility. "
+                "In the future, we will require at least one of these fields."
+            )
+        return self
diff --git a/tests/test_identifiers.py b/tests/test_identifiers.py
index 780ae0d4d..155341ab3 100644
--- a/tests/test_identifiers.py
+++ b/tests/test_identifiers.py
@@ -4,7 +4,7 @@
 
 from pydantic import ValidationError
 
-from aind_data_schema.components.identifiers import Person
+from aind_data_schema.components.identifiers import Code, Person
 
 
 class Testexperimenter(unittest.TestCase):
@@ -23,5 +23,36 @@ def test_experimenter_missing_fields(self):
             Person()
 
 
+class TestGitHash(unittest.TestCase):
+    """Test GitHash type validation via Code model"""
+
+    def test_git_hash_valid(self):
+        """Valid git hashes are accepted and stored correctly"""
+        cases = [
+            ("abc1234", "abc1234"),
+            ("a" * 40, "a" * 40),
+            ("a" * 60, "a" * 60),
+            ("aBcDeF1", "aBcDeF1"),
+            ("deadbeef1234", "deadbeef1234"),
+            ("  abc1234  ", "abc1234"),  # strip_whitespace=True strips before validation
+        ]
+        for git_hash, expected in cases:
+            with self.subTest(git_hash=git_hash):
+                code = Code(url="https://github.com/org/repo", commit_hash=git_hash)
+                self.assertEqual(code.commit_hash, expected)
+
+    def test_git_hash_invalid(self):
+        """Invalid git hashes raise ValidationError"""
+        cases = [
+            "abc123",  # too short (6 chars)
+            "a" * 61,  # too long (61 chars)
+            "xyz12345",  # non-hex characters
+        ]
+        for git_hash in cases:
+            with self.subTest(git_hash=git_hash):
+                with self.assertRaises(ValidationError):
+                    Code(url="https://github.com/org/repo", commit_hash=git_hash)
+
+
 if __name__ == "__main__":
     unittest.main()