diff --git a/git_config.py b/git_config.py
index 282c080..914b292 100644
--- a/git_config.py
+++ b/git_config.py
@@ -145,6 +145,21 @@ class GitConfig(object):
     except ValueError:
       return None
 
+  def DumpConfigDict(self):
+    """Returns the current configuration dict.
+
+    Configuration data is information only (e.g. logging) and
+    should not be considered a stable data-source.
+
+    Returns:
+      dict of {<key>, <value>} for git configuration cache.
+      <value> are strings converted by GetString.
+    """
+    config_dict = {}
+    for key in self._cache:
+      config_dict[key] = self.GetString(key)
+    return config_dict
+
   def GetBoolean(self, name):
     """Returns a boolean from the configuration file.
        None : The value was not defined, or is not a boolean.
diff --git a/git_trace2_event_log.py b/git_trace2_event_log.py
index fe34092..8c33d80 100644
--- a/git_trace2_event_log.py
+++ b/git_trace2_event_log.py
@@ -132,6 +132,21 @@ class EventLog(object):
     exit_event['code'] = result
     self._log.append(exit_event)
 
+  def DefParamRepoEvents(self, config):
+    """Append a 'def_param' event for each repo.* config key to the current log.
+
+    Args:
+      config: Repo configuration dictionary
+    """
+    # Only output the repo.* config parameters.
+    repo_config = {k: v for k, v in config.items() if k.startswith('repo.')}
+
+    for param, value in repo_config.items():
+      def_param_event = self._CreateEventDict('def_param')
+      def_param_event['param'] = param
+      def_param_event['value'] = value
+      self._log.append(def_param_event)
+
   def _GetEventTargetPath(self):
     """Get the 'trace2.eventtarget' path from git configuration.
 
diff --git a/main.py b/main.py
index f638a67..ba5d9d2 100755
--- a/main.py
+++ b/main.py
@@ -297,6 +297,8 @@ class _Repo(object):
 
       cmd.event_log.FinishEvent(cmd_event, finish,
                                 result is None or result == 0)
+      git_trace2_event_log.DefParamRepoEvents(
+          cmd.manifest.manifestProject.config.DumpConfigDict())
       git_trace2_event_log.ExitEvent(result)
 
       if gopts.event_log:
diff --git a/tests/test_git_trace2_event_log.py b/tests/test_git_trace2_event_log.py
index 8fb38db..3c5cb15 100644
--- a/tests/test_git_trace2_event_log.py
+++ b/tests/test_git_trace2_event_log.py
@@ -161,6 +161,55 @@ class EventLogTestCase(unittest.TestCase):
     self.assertIn('code', exit_event)
     self.assertEqual(exit_event['code'], 2)
 
+  def test_def_params_event_repo_config(self):
+    """Test 'def_params' event data outputs only repo config keys.
+
+    Expected event log:
+    <version event>
+    <def_param event>
+    <def_param event>
+    """
+    config = {
+        'git.foo': 'bar',
+        'repo.partialclone': 'true',
+        'repo.partialclonefilter': 'blob:none',
+    }
+    self._event_log_module.DefParamRepoEvents(config)
+
+    with tempfile.TemporaryDirectory(prefix='event_log_tests') as tempdir:
+      log_path = self._event_log_module.Write(path=tempdir)
+      self._log_data = self.readLog(log_path)
+
+    self.assertEqual(len(self._log_data), 3)
+    def_param_events = self._log_data[1:]
+    self.verifyCommonKeys(self._log_data[0], expected_event_name='version')
+
+    for event in def_param_events:
+      self.verifyCommonKeys(event, expected_event_name='def_param')
+      # Check for 'def_param' event specific fields.
+      self.assertIn('param', event)
+      self.assertIn('value', event)
+      self.assertTrue(event['param'].startswith('repo.'))
+
+  def test_def_params_event_no_repo_config(self):
+    """Test 'def_params' event data won't output non-repo config keys.
+
+    Expected event log:
+    <version event>
+    """
+    config = {
+        'git.foo': 'bar',
+        'git.core.foo2': 'baz',
+    }
+    self._event_log_module.DefParamRepoEvents(config)
+
+    with tempfile.TemporaryDirectory(prefix='event_log_tests') as tempdir:
+      log_path = self._event_log_module.Write(path=tempdir)
+      self._log_data = self.readLog(log_path)
+
+    self.assertEqual(len(self._log_data), 1)
+    self.verifyCommonKeys(self._log_data[0], expected_event_name='version')
+
   def test_write_with_filename(self):
     """Test Write() with a path to a file exits with None."""
     self.assertIsNone(self._event_log_module.Write(path='path/to/file'))