diff --git a/addons/api/addon/models/role.js b/addons/api/addon/models/role.js
index f4f25df61..dd7e8bb2b 100644
--- a/addons/api/addon/models/role.js
+++ b/addons/api/addon/models/role.js
@@ -36,4 +36,64 @@ export default class RoleModel extends GeneratedRoleModel {
     });
   }
 
+  /**
+   * Adds principals via the `add-principals` method.
+   * See serializer and adapter for more information.
+   * @param {[string]} principalIDs
+   * @param {object} options
+   * @param {object} options.adapterOptions
+   * @return {Promise}
+   */
+  addPrincipals(principalIDs, options={ adapterOptions: {} }) {
+    const defaultAdapterOptions = {
+      method: 'add-principals',
+      principalIDs
+    };
+    // There is no "deep merge" in ES.
+    // All of this nonsense is here to ensure we get
+    // a decent merge of `adapterOptions`.
+    return this.save({
+      ...options,
+      adapterOptions: {
+        ...defaultAdapterOptions,
+        ...options.adapterOptions
+      }
+    });
+  }
+
+  /**
+   * Delete principals via the `remove-principals` method.
+   * See serializer and adapter for more information.
+   * @param {[string]} principalIDs
+   * @param {object} options
+   * @param {object} options.adapterOptions
+   * @return {Promise}
+   */
+  removePrincipals(principalIDs, options={ adapterOptions: {} }) {
+    const defaultAdapterOptions = {
+      method: 'remove-principals',
+      principalIDs
+    };
+    // There is no "deep merge" in ES.
+    // All of this nonsense is here to ensure we get
+    // a decent merge of `adapterOptions`.
+    return this.save({
+      ...options,
+      adapterOptions: {
+        ...defaultAdapterOptions,
+        ...options.adapterOptions
+      }
+    });
+  }
+
+  /**
+   * Delete a single principal via the `remove-principals` method.
+   * @param {number} principalIDs
+   * @param {object} options
+   * @return {Promise}
+   */
+  removePrincipal(principalID, options) {
+    return this.removePrincipals([principalID], options);
+  }
+
 }
diff --git a/addons/api/addon/serializers/role.js b/addons/api/addon/serializers/role.js
index 9cf12da58..5479d051e 100644
--- a/addons/api/addon/serializers/role.js
+++ b/addons/api/addon/serializers/role.js
@@ -9,6 +9,8 @@ export default class RoleSerializer extends ApplicationSerializer {
    * If `adapterOptions.serializeGrants` is true, the serialization should
    * include **only grants** and the version.  Normally, grants are not
    * serialized.
+   * If `adapterOptions.principalIDs` is set (to an array of user and
+   * group IDs), then the payload is serialized via `serializeWithPrincipals`.
    * @override
    * @param {Snapshot} snapshot
    * @return {object}
@@ -17,6 +19,9 @@ export default class RoleSerializer extends ApplicationSerializer {
     const serializeGrants = get(snapshot, 'adapterOptions.serializeGrants');
     let serialized = super.serialize(...arguments);
     if (serializeGrants) serialized = this.serializeWithGrants(snapshot);
+    const principalIDs = snapshot?.adapterOptions?.principalIDs;
+    if (principalIDs) serialized =
+      this.serializeWithPrincipals(snapshot, principalIDs);
     return serialized;
   }
 
@@ -32,6 +37,20 @@ export default class RoleSerializer extends ApplicationSerializer {
     };
   }
 
+  /**
+   * Returns a payload containing only the principal_ids array using IDs
+   * passed into the function (rather than existing principals on the model).
+   * @param {Snapshot} snapshot
+   * @param {[string]} principalIDs
+   * @return {object}
+   */
+  serializeWithPrincipals(snapshot, principalIDs) {
+    return {
+      version: snapshot.attr('version'),
+      principal_ids: principalIDs
+    };
+  }
+
   /**
    * Converts string arrays to object arrays for use with `fragment-string`.
    * E.g. `"foo"` -> `{value: "foo"}`
diff --git a/addons/api/tests/unit/models/role-test.js b/addons/api/tests/unit/models/role-test.js
index fe1b8224b..50a0fdb2d 100644
--- a/addons/api/tests/unit/models/role-test.js
+++ b/addons/api/tests/unit/models/role-test.js
@@ -41,4 +41,103 @@ module('Unit | Model | role', function (hooks) {
     const model = store.peekRecord('role', '123abc');
     await model.saveGrants();
   });
+
+  test('it has an `addPrincipals` method that targets a specific POST API endpoint and serialization', async function (assert) {
+    assert.expect(1);
+    this.server.post('/v1/scopes/o_1/roles/123abc:add-principals', (schema, request) => {
+      const body = JSON.parse(request.requestBody);
+      assert.deepEqual(body, {
+        principal_ids: ['123_abc', 'foobar'],
+        version: 1
+      });
+    });
+    const store = this.owner.lookup('service:store');
+    store.push({
+      data: {
+        id: '123abc',
+        type: 'role',
+        attributes: {
+          name: 'Role',
+          description: 'Description',
+          principals: [
+            { id: '1', type: 'user' },
+            { id: '3', type: 'group' }
+          ],
+          version: 1,
+          scope: {
+            scope_id: 'o_1',
+            type: 'scope'
+          }
+        }
+      }
+    });
+    const model = store.peekRecord('role', '123abc');
+    await model.addPrincipals(['123_abc', 'foobar']);
+  });
+
+  test('it has a `removePrincipals` method that targets a specific POST API endpoint and serialization', async function (assert) {
+    assert.expect(1);
+    this.server.post('/v1/scopes/o_1/roles/123abc:remove-principals', (schema, request) => {
+      const body = JSON.parse(request.requestBody);
+      assert.deepEqual(body, {
+        principal_ids: ['1', '3'],
+        version: 1
+      });
+    });
+    const store = this.owner.lookup('service:store');
+    store.push({
+      data: {
+        id: '123abc',
+        type: 'role',
+        attributes: {
+          name: 'Role',
+          description: 'Description',
+          principals: [
+            { id: '1', type: 'user' },
+            { id: '3', type: 'group' }
+          ],
+          version: 1,
+          scope: {
+            scope_id: 'o_1',
+            type: 'scope'
+          }
+        }
+      }
+    });
+    const model = store.peekRecord('role', '123abc');
+    await model.removePrincipals(['1', '3']);
+  });
+
+  test('it has a `removePrincipal` method that deletes a single principal using `removePrincipals` method', async function (assert) {
+    assert.expect(1);
+    this.server.post('/v1/scopes/o_1/roles/123abc:remove-principals', (schema, request) => {
+      const body = JSON.parse(request.requestBody);
+      assert.deepEqual(body, {
+        principal_ids: ['3'],
+        version: 1
+      });
+    });
+    const store = this.owner.lookup('service:store');
+    store.push({
+      data: {
+        id: '123abc',
+        type: 'role',
+        attributes: {
+          name: 'Role',
+          description: 'Description',
+          principals: [
+            { id: '1', type: 'user' },
+            { id: '3', type: 'group' }
+          ],
+          version: 1,
+          scope: {
+            scope_id: 'o_1',
+            type: 'scope'
+          }
+        }
+      }
+    });
+    const model = store.peekRecord('role', '123abc');
+    await model.removePrincipal('3');
+  });
 });