diff --git a/core/api/current.txt b/core/api/current.txt
index 0ce315adc3104..f58e4260a09ed 100644
--- a/core/api/current.txt
+++ b/core/api/current.txt
@@ -32515,6 +32515,7 @@ package android.os {
     method public static final boolean is64Bit();
     method public static boolean isApplicationUid(int);
     method public static final boolean isIsolated();
+    method public static final boolean isSupplemental();
     method public static final void killProcess(int);
     method public static final int myPid();
     method @NonNull public static String myProcessName();
diff --git a/core/api/module-lib-current.txt b/core/api/module-lib-current.txt
index 9abf00bb250b8..dbb26ac647a55 100644
--- a/core/api/module-lib-current.txt
+++ b/core/api/module-lib-current.txt
@@ -376,6 +376,9 @@ package android.os {
   }
 
   public class Process {
+    method public static final boolean isSupplemental(int);
+    method public static final int toAppUid(int);
+    method public static final int toSupplementalUid(int);
     field public static final int NFC_UID = 1027; // 0x403
     field public static final int VPN_UID = 1016; // 0x3f8
   }
diff --git a/core/java/android/os/Process.java b/core/java/android/os/Process.java
index a63f68a343d27..2fe0622681127 100644
--- a/core/java/android/os/Process.java
+++ b/core/java/android/os/Process.java
@@ -279,6 +279,26 @@ public class Process {
      */
     public static final int LAST_APPLICATION_UID = 19999;
 
+    /**
+     * Defines the start of a range of UIDs going from this number to
+     * {@link #LAST_SUPPLEMENTAL_UID} that are reserved for assigning to
+     * supplemental processes. There is a 1-1 mapping between a supplemental
+     * process UID and the app that it belongs to, which can be computed by
+     * subtracting (FIRST_SUPPLEMENTAL_UID - FIRST_APPLICATION_UID) from the
+     * uid of a supplemental process.
+     *
+     * Note that there are no GIDs associated with these processes; storage
+     * attribution for them will be done using project IDs.
+     * @hide
+     */
+    public static final int FIRST_SUPPLEMENTAL_UID = 20000;
+
+    /**
+     * Last UID that is used for supplemental processes.
+     * @hide
+     */
+    public static final int LAST_SUPPLEMENTAL_UID = 29999;
+
     /**
      * First uid used for fully isolated sandboxed processes spawned from an app zygote
      * @hide
@@ -880,6 +900,46 @@ public class Process {
                 || (uid >= FIRST_APP_ZYGOTE_ISOLATED_UID && uid <= LAST_APP_ZYGOTE_ISOLATED_UID);
     }
 
+    /**
+     * Returns whether the provided UID belongs to a supplemental process.
+     *
+     * @hide
+     */
+    @SystemApi(client = MODULE_LIBRARIES)
+    public static final boolean isSupplemental(int uid) {
+        uid = UserHandle.getAppId(uid);
+        return (uid >= FIRST_SUPPLEMENTAL_UID && uid <= LAST_SUPPLEMENTAL_UID);
+    }
+
+    /**
+     *
+     * Returns the app process corresponding to a supplemental process.
+     *
+     * @hide
+     */
+    @SystemApi(client = MODULE_LIBRARIES)
+    public static final int toAppUid(int uid) {
+        return uid - (FIRST_SUPPLEMENTAL_UID - FIRST_APPLICATION_UID);
+    }
+
+    /**
+     *
+     * Returns the supplemental process corresponding to an app process.
+     *
+     * @hide
+     */
+    @SystemApi(client = MODULE_LIBRARIES)
+    public static final int toSupplementalUid(int uid) {
+        return uid + (FIRST_SUPPLEMENTAL_UID - FIRST_APPLICATION_UID);
+    }
+
+    /**
+     * Returns whether the current process is a supplemental process.
+     */
+    public static final boolean isSupplemental() {
+        return isSupplemental(myUid());
+    }
+
     /**
      * Returns the UID assigned to a particular user name, or -1 if there is
      * none.  If the given string consists of only numbers, it is converted