diff --git a/libs/microdroid_uids/Android.bp b/libs/microdroid_uids/Android.bp
new file mode 100644
index 0000000..497948d
--- /dev/null
+++ b/libs/microdroid_uids/Android.bp
@@ -0,0 +1,15 @@
+package {
+    default_applicable_licenses: ["Android-Apache-2.0"],
+}
+
+rust_library {
+    name: "libmicrodroid_uids",
+    crate_name: "microdroid_uids",
+    srcs: ["src/lib.rs"],
+    edition: "2021",
+    // TODO(b/296393106): Figure out how/when to enable this
+    // cfgs: ["payload_not_root"],
+    apex_available: [
+        "com.android.virt",
+    ],
+}
diff --git a/libs/microdroid_uids/src/lib.rs b/libs/microdroid_uids/src/lib.rs
new file mode 100644
index 0000000..1f09c65
--- /dev/null
+++ b/libs/microdroid_uids/src/lib.rs
@@ -0,0 +1,24 @@
+// Copyright 2023 The Android Open Source Project
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//      http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+//! User and group IDs within Microdroid
+
+/// Always the user ID of Root.
+pub const ROOT_UID: u32 = 0;
+
+/// Group ID shared by all payload users.
+pub const MICRODROID_PAYLOAD_GID: u32 = if cfg!(payload_not_root) { 6000 } else { 0 };
+
+/// User ID for the initial payload user.
+pub const MICRODROID_PAYLOAD_UID: u32 = if cfg!(payload_not_root) { 6000 } else { 0 };