diff --git a/git_trace2_event_log.py b/git_trace2_event_log.py
index 9c9e5a7..92c4cc6 100644
--- a/git_trace2_event_log.py
+++ b/git_trace2_event_log.py
@@ -167,6 +167,22 @@
     repo_config = {k: v for k, v in config.items() if k.startswith('repo.')}
     self.LogConfigEvents(repo_config, 'def_param')
 
+  def LogDataConfigEvents(self, config, prefix):
+    """Append a 'data' event for each config key/value in |config| to the current log.
+
+    For each keyX and valueX of the config, "key" field of the event is '|prefix|/keyX'
+    and the "value" of the "key" field is valueX.
+
+    Args:
+      config: Configuration dictionary.
+      prefix: Prefix for each key that is logged.
+    """
+    for key, value in config.items():
+      event = self._CreateEventDict('data')
+      event['key'] = f'{prefix}/{key}'
+      event['value'] = value
+      self._log.append(event)
+
   def ErrorEvent(self, msg, fmt):
     """Append a 'error' event to the current log."""
     error_event = self._CreateEventDict('error')
diff --git a/subcmds/sync.py b/subcmds/sync.py
index 2a0de0a..c99b06c 100644
--- a/subcmds/sync.py
+++ b/subcmds/sync.py
@@ -1092,13 +1092,13 @@
       sys.exit(1)
 
     # Log the previous sync analysis state from the config.
-    self.git_event_log.LogConfigEvents(mp.config.GetSyncAnalysisStateData(),
-                                       'previous_sync_state')
+    self.git_event_log.LogDataConfigEvents(mp.config.GetSyncAnalysisStateData(),
+                                           'previous_sync_state')
 
     # Update and log with the new sync analysis state.
     mp.config.UpdateSyncAnalysisState(opt, superproject_logging_data)
-    self.git_event_log.LogConfigEvents(mp.config.GetSyncAnalysisStateData(),
-                                       'current_sync_state')
+    self.git_event_log.LogDataConfigEvents(mp.config.GetSyncAnalysisStateData(),
+                                           'current_sync_state')
 
     if not opt.quiet:
       print('repo sync has finished successfully.')
diff --git a/tests/fixtures/test.gitconfig b/tests/fixtures/test.gitconfig
index 90afff0..b178cf6 100644
--- a/tests/fixtures/test.gitconfig
+++ b/tests/fixtures/test.gitconfig
@@ -12,7 +12,7 @@
 	intm = 10m
 	intg = 10g
 [repo "syncstate.main"]
-	synctime = 2021-08-13T18:37:43.928600Z
+	synctime = 2021-09-14T17:23:43.537338Z
 	version = 1
 [repo "syncstate.sys"]
 	argv = ['/usr/bin/pytest-3']
diff --git a/tests/test_git_trace2_event_log.py b/tests/test_git_trace2_event_log.py
index bee5865..a5a6cbb 100644
--- a/tests/test_git_trace2_event_log.py
+++ b/tests/test_git_trace2_event_log.py
@@ -234,6 +234,39 @@
     self.assertEqual(len(self._log_data), 1)
     self.verifyCommonKeys(self._log_data[0], expected_event_name='version')
 
+  def test_data_event_config(self):
+    """Test 'data' event data outputs all config keys.
+
+    Expected event log:
+    <version event>
+    <data event>
+    <data event>
+    """
+    config = {
+        'git.foo': 'bar',
+        'repo.partialclone': 'false',
+        'repo.syncstate.superproject.hassuperprojecttag': 'true',
+    }
+    prefix_value = 'prefix'
+    self._event_log_module.LogDataConfigEvents(config, prefix_value)
+
+    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), 4)
+    data_events = self._log_data[1:]
+    self.verifyCommonKeys(self._log_data[0], expected_event_name='version')
+
+    for event in data_events:
+      self.verifyCommonKeys(event, expected_event_name='data')
+      # Check for 'data' event specific fields.
+      self.assertIn('key', event)
+      self.assertIn('value', event)
+      key = event['key'].removeprefix(f'{prefix_value}/')
+      value = event['value']
+      self.assertTrue(key in config and value == config[key])
+
   def test_error_event(self):
     """Test and validate 'error' event data is valid.