diff --git a/components/nimbus/src/cirrus.udl b/components/nimbus/src/cirrus.udl
index 05bc24e310..49a984b990 100644
--- a/components/nimbus/src/cirrus.udl
+++ b/components/nimbus/src/cirrus.udl
@@ -12,7 +12,7 @@ enum NimbusError {
 };
 
 callback interface MetricsHandler {
-    void record_enrollment_statuses(sequence<EnrollmentStatusExtraDef> enrollment_status_extras);
+    void record_enrollment_statuses_v2(sequence<EnrollmentStatusExtraDef> enrollment_status_extras, string? nimbus_user_id);
 };
 
 dictionary EnrollmentStatusExtraDef {
diff --git a/components/nimbus/src/metrics.rs b/components/nimbus/src/metrics.rs
index 6a21dc1f04..39fff19036 100644
--- a/components/nimbus/src/metrics.rs
+++ b/components/nimbus/src/metrics.rs
@@ -9,8 +9,16 @@ use crate::{enrollment::ExperimentEnrollment, EnrolledFeature, EnrollmentStatus}
 use serde_derive::{Deserialize, Serialize};
 
 pub trait MetricsHandler: Send + Sync {
+    #[cfg(feature = "stateful")]
     fn record_enrollment_statuses(&self, enrollment_status_extras: Vec<EnrollmentStatusExtraDef>);
 
+    #[cfg(not(feature = "stateful"))]
+    fn record_enrollment_statuses_v2(
+        &self,
+        enrollment_status_extras: Vec<EnrollmentStatusExtraDef>,
+        nimbus_user_id: Option<String>,
+    );
+
     #[cfg(feature = "stateful")]
     fn record_feature_activation(&self, event: FeatureExposureExtraDef);
 
diff --git a/components/nimbus/src/stateless/cirrus_client.rs b/components/nimbus/src/stateless/cirrus_client.rs
index 33e175f43d..9c1dcbf0fa 100644
--- a/components/nimbus/src/stateless/cirrus_client.rs
+++ b/components/nimbus/src/stateless/cirrus_client.rs
@@ -149,7 +149,7 @@ impl CirrusClient {
                 prev_enrollments,
             )?;
 
-        self.metrics_handler.record_enrollment_statuses(
+        self.metrics_handler.record_enrollment_statuses_v2(
             enrollments
                 .iter()
                 .cloned()
@@ -159,6 +159,7 @@ impl CirrusClient {
                     extra
                 })
                 .collect(),
+            Some(user_id.clone()),
         );
 
         let enrolled_feature_config_map =
diff --git a/components/nimbus/src/tests/helpers.rs b/components/nimbus/src/tests/helpers.rs
index e31a5d689b..57f7d8a46f 100644
--- a/components/nimbus/src/tests/helpers.rs
+++ b/components/nimbus/src/tests/helpers.rs
@@ -154,6 +154,8 @@ struct MetricState {
     exposures: Vec<FeatureExposureExtraDef>,
     #[cfg(feature = "stateful")]
     malformeds: Vec<MalformedFeatureConfigExtraDef>,
+    #[cfg(not(feature = "stateful"))]
+    nimbus_user_id: Option<String>,
 }
 
 /// A Rust implementation of the MetricsHandler trait
@@ -175,6 +177,11 @@ impl TestMetrics {
     pub fn get_enrollment_statuses(&self) -> Vec<EnrollmentStatusExtraDef> {
         self.state.lock().unwrap().enrollment_statuses.clone()
     }
+
+    #[cfg(not(feature = "stateful"))]
+    pub fn get_nimbus_user_id(&self) -> Option<String> {
+        self.state.lock().unwrap().nimbus_user_id.clone()
+    }
 }
 
 #[cfg(feature = "stateful")]
@@ -196,11 +203,23 @@ impl TestMetrics {
 }
 
 impl MetricsHandler for TestMetrics {
+    #[cfg(feature = "stateful")]
     fn record_enrollment_statuses(&self, enrollment_status_extras: Vec<EnrollmentStatusExtraDef>) {
         let mut state = self.state.lock().unwrap();
         state.enrollment_statuses.extend(enrollment_status_extras);
     }
 
+    #[cfg(not(feature = "stateful"))]
+    fn record_enrollment_statuses_v2(
+        &self,
+        enrollment_status_extras: Vec<EnrollmentStatusExtraDef>,
+        nimbus_user_id: Option<String>,
+    ) {
+        let mut state = self.state.lock().unwrap();
+        state.enrollment_statuses.extend(enrollment_status_extras);
+        state.nimbus_user_id = nimbus_user_id;
+    }
+
     #[cfg(feature = "stateful")]
     fn record_feature_activation(&self, event: FeatureExposureExtraDef) {
         let mut state = self.state.lock().unwrap();
diff --git a/components/nimbus/src/tests/stateless/test_cirrus_client.rs b/components/nimbus/src/tests/stateless/test_cirrus_client.rs
index 2652e7fee1..cae5537cff 100644
--- a/components/nimbus/src/tests/stateless/test_cirrus_client.rs
+++ b/components/nimbus/src/tests/stateless/test_cirrus_client.rs
@@ -205,6 +205,9 @@ fn test_sends_metrics_on_enrollment() -> Result<()> {
     assert_eq!(metric_records[0].branch(), "treatment");
     assert_eq!(metric_records[0].user_id(), "test");
 
+    let nimbus_user_id: Option<String> = metrics_handler.get_nimbus_user_id();
+    assert_eq!(nimbus_user_id, Some("test".into()));
+
     Ok(())
 }
 
diff --git a/components/nimbus/tests/common/mod.rs b/components/nimbus/tests/common/mod.rs
index c0db8282eb..2fb39314d8 100644
--- a/components/nimbus/tests/common/mod.rs
+++ b/components/nimbus/tests/common/mod.rs
@@ -17,10 +17,16 @@ use nimbus::{
 pub struct NoopMetricsHandler;
 
 impl MetricsHandler for NoopMetricsHandler {
+    #[cfg(feature = "stateful")]
     fn record_enrollment_statuses(&self, _: Vec<EnrollmentStatusExtraDef>) {
         // do nothing
     }
 
+    #[cfg(not(feature = "stateful"))]
+    fn record_enrollment_statuses_v2(&self, _: Vec<EnrollmentStatusExtraDef>, _: Option<String>) {
+        // do nothing
+    }
+
     #[cfg(feature = "stateful")]
     fn record_feature_activation(&self, _activation_event: FeatureExposureExtraDef) {
         // do nothing
diff --git a/megazords/cirrus/tests/python-tests/conftest.py b/megazords/cirrus/tests/python-tests/conftest.py
index ba66c821d8..67ffe6cdb1 100644
--- a/megazords/cirrus/tests/python-tests/conftest.py
+++ b/megazords/cirrus/tests/python-tests/conftest.py
@@ -10,12 +10,14 @@
 
 class TestMetricsHandler(MetricsHandler):
     recordings = []
+    nimbus_user_id = None
 
-    def record_enrollment_statuses(
-        self, enrollment_status_extras: [EnrollmentStatusExtraDef]
+    def record_enrollment_statuses_v2(
+        self, enrollment_status_extras: [EnrollmentStatusExtraDef], nimbus_user_id: str
     ):
         self.recordings.clear()
         self.recordings.extend(enrollment_status_extras)
+        self.nimbus_user_id = nimbus_user_id
 
 
 @pytest.fixture
diff --git a/megazords/cirrus/tests/python-tests/test_cirrus.py b/megazords/cirrus/tests/python-tests/test_cirrus.py
index 14946a417a..afe9eb9935 100644
--- a/megazords/cirrus/tests/python-tests/test_cirrus.py
+++ b/megazords/cirrus/tests/python-tests/test_cirrus.py
@@ -60,3 +60,4 @@ def test_metrics_handler(app_context, experiment, req):
     json.loads(client.handle_enrollment(req()))
 
     assert len(test_metrics.recordings) == 1
+    assert test_metrics.nimbus_user_id