diff --git a/core/api/src/main/java/org/onlab/onos/cluster/MastershipStore.java b/core/api/src/main/java/org/onlab/onos/cluster/MastershipStore.java
new file mode 100644
index 0000000..dad4a75
--- /dev/null
+++ b/core/api/src/main/java/org/onlab/onos/cluster/MastershipStore.java
@@ -0,0 +1,61 @@
+package org.onlab.onos.cluster;
+
+import java.util.Set;
+
+import org.onlab.onos.net.DeviceId;
+import org.onlab.onos.net.MastershipRole;
+
+/**
+ * Manages inventory of mastership roles for devices, across controller instances.
+ */
+public interface MastershipStore {
+
+    // three things to map: InstanceId, DeviceId, MastershipRole
+
+    /**
+     * Sets a device's role for a specified controller instance.
+     *
+     * @param instance controller instance identifier
+     * @param deviceId device identifier
+     * @param role     new role
+     * @return a mastership event
+     */
+    MastershipEvent setRole(
+            InstanceId instance, DeviceId deviceId, MastershipRole role);
+
+    /**
+     * Adds or updates the mastership information for a device.
+     *
+     * @param instance controller instance identifier
+     * @param deviceId device identifier
+     * @param role     new role
+     * @return a mastership event
+     */
+    MastershipEvent addOrUpdateDevice(
+            InstanceId instance, DeviceId deviceId, MastershipRole role);
+
+    /**
+     * Returns the master for a device.
+     *
+     * @param deviceId the device identifier
+     * @return the instance identifier of the master
+     */
+    InstanceId getMaster(DeviceId deviceId);
+
+    /**
+     * Returns the devices that a controller instance is master of.
+     *
+     * @param  instanceId the instance identifier
+     * @return a set of device identifiers
+     */
+    Set<DeviceId> getDevices(InstanceId instanceId);
+
+    /**
+     * Returns the role of a device for a specific controller instance.
+     *
+     * @param instanceId the instance identifier
+     * @param deviceId the device identifiers
+     * @return the role
+     */
+    MastershipRole getRole(InstanceId instanceId, DeviceId deviceId);
+}