diff --git a/packages/arcgis-rest-service-admin/src/index.ts b/packages/arcgis-rest-service-admin/src/index.ts
index 3b8e5c9014..9c66fd4026 100644
--- a/packages/arcgis-rest-service-admin/src/index.ts
+++ b/packages/arcgis-rest-service-admin/src/index.ts
@@ -1,5 +1,6 @@
 export * from "./create";
 export * from "./addTo";
+export * from "./update";
 export {
   IFeatureServiceDefinition,
   IExtent,
diff --git a/packages/arcgis-rest-service-admin/src/update.ts b/packages/arcgis-rest-service-admin/src/update.ts
new file mode 100644
index 0000000000..3ac96c87ff
--- /dev/null
+++ b/packages/arcgis-rest-service-admin/src/update.ts
@@ -0,0 +1,50 @@
+/* Copyright (c) 2018-2019 Environmental Systems Research Institute, Inc.
+ * Apache-2.0 */
+
+import { request, cleanUrl } from "@esri/arcgis-rest-request";
+import { IFeatureServiceDefinition } from "@esri/arcgis-rest-types";
+import { IUserRequestOptions } from "@esri/arcgis-rest-auth";
+
+export interface IUpdateServiceDefinitionOptions extends IUserRequestOptions {
+  updateDefinition?: Partial<IFeatureServiceDefinition>;
+}
+
+export interface IUpdateServiceDefinitionResult {
+  success: boolean;
+}
+
+/**
+ * ```js
+ * import { updateServiceDefinition } from '@esri/arcgis-rest-service-admin';
+ * //
+ * updateServiceDefinition(serviceurl, {
+ *   authentication: userSession,
+ *   updateDefinition: serviceDefinition
+ * });
+ * ```
+ * Update a definition property in a hosted feature service. See the [REST Documentation](https://developers.arcgis.com/rest/services-reference/update-definition-feature-service-.htm) for more information.
+ *
+ * @param url - URL of feature service
+ * @param requestOptions - Options for the request
+ * @returns A Promise that resolves with success or error
+ */
+export function updateServiceDefinition(
+  url: string,
+  requestOptions: IUpdateServiceDefinitionOptions
+): Promise<IUpdateServiceDefinitionResult> {
+  const adminUrl = `${cleanUrl(url).replace(
+    `/rest/services`,
+    `/rest/admin/services`
+  )}/updateDefinition`;
+
+  requestOptions.params = {
+    updateDefinition: {},
+    ...requestOptions.params
+  };
+
+  if (requestOptions.updateDefinition) {
+    requestOptions.params.updateDefinition = requestOptions.updateDefinition;
+  }
+
+  return request(adminUrl, requestOptions);
+}
diff --git a/packages/arcgis-rest-service-admin/test/mocks/service.ts b/packages/arcgis-rest-service-admin/test/mocks/service.ts
index 70c1742a3a..f15c035339 100644
--- a/packages/arcgis-rest-service-admin/test/mocks/service.ts
+++ b/packages/arcgis-rest-service-admin/test/mocks/service.ts
@@ -3,6 +3,7 @@
 
 import { ICreateServiceResult } from "../../src/create";
 import { IAddToServiceDefinitionResult } from "../../src/addTo";
+import { IUpdateServiceDefinitionResult } from "../../src/update";
 
 export const FeatureServiceResponse: ICreateServiceResult = {
   encodedServiceURL:
@@ -67,3 +68,14 @@ export const AddToFeatureServiceError: any = {
     details: ["Object reference not set to an instance of an object."]
   }
 };
+
+export const UpdateServiceDefinitionSuccess: IUpdateServiceDefinitionResult = {
+  success: true
+}
+export const UpdateServiceDefinitionError: any = {
+  error: {
+    code: 400,
+    message: "Invalid URL",
+    details: ["Invalid URL"]
+  }
+};
diff --git a/packages/arcgis-rest-service-admin/test/update.test.ts b/packages/arcgis-rest-service-admin/test/update.test.ts
new file mode 100644
index 0000000000..f3869ba470
--- /dev/null
+++ b/packages/arcgis-rest-service-admin/test/update.test.ts
@@ -0,0 +1,115 @@
+/* Copyright (c) 2018 Environmental Systems Research Institute, Inc.
+ * Apache-2.0 */
+
+import * as fetchMock from "fetch-mock";
+
+import { UserSession } from "@esri/arcgis-rest-auth";
+import { TOMORROW } from "@esri/arcgis-rest-auth/test/utils";
+import { encodeParam } from "@esri/arcgis-rest-request";
+import { updateServiceDefinition } from "../src/update";
+import { UpdateServiceDefinitionSuccess } from "./mocks/service";
+
+describe("update service definition", () => {
+  afterEach(fetchMock.restore);
+
+  describe("Authenticated methods", () => {
+    // setup a UserSession to use in all these tests
+    const MOCK_USER_SESSION = new UserSession({
+      clientId: "clientId",
+      redirectUri: "https://example-app.com/redirect-uri",
+      token: "fake-token",
+      tokenExpires: TOMORROW,
+      refreshToken: "refreshToken",
+      refreshTokenExpires: TOMORROW,
+      refreshTokenTTL: 1440,
+      username: "casey",
+      password: "123456",
+      portal: "https://myorg.maps.arcgis.com/sharing/rest"
+    });
+
+    const MOCK_USER_REQOPTS = {
+      authentication: MOCK_USER_SESSION
+    };
+
+    const updateDefinition = {
+      capabilities: 'Create,Update'
+    };
+
+    it("should update feature service defintion", done => {
+      fetchMock.once("*", UpdateServiceDefinitionSuccess);
+
+      updateServiceDefinition(
+        "https://services1.arcgis.com/ORG/arcgis/rest/services/FEATURE_SERVICE/FeatureServer",
+        {
+          updateDefinition,
+          ...MOCK_USER_REQOPTS
+        }
+      )
+        .then(response => {
+          // Check service call
+          expect(fetchMock.called()).toEqual(true);
+          const [url, options]: [string, RequestInit] = fetchMock.lastCall("*");
+
+          expect(url).toEqual(
+            "https://services1.arcgis.com/ORG/arcgis/rest/admin/services/FEATURE_SERVICE/FeatureServer/updateDefinition"
+          );
+          expect(options.method).toBe("POST");
+          expect(options.body).toContain("f=json");
+          expect(options.body).toContain(encodeParam("token", "fake-token"));
+          expect(options.body).toContain(
+            encodeParam(
+              "updateDefinition",
+              JSON.stringify(updateDefinition)
+            )
+          );
+
+          // Check response
+          expect(response).toEqual(
+            UpdateServiceDefinitionSuccess
+          );
+          done();
+        })
+        .catch(e => {
+          fail(e);
+        });
+    });
+    it("should update feature service defintion (params.updateDefinition)", done => {
+      fetchMock.once("*", UpdateServiceDefinitionSuccess);
+
+      updateServiceDefinition(
+        "https://services1.arcgis.com/ORG/arcgis/rest/services/FEATURE_SERVICE/FeatureServer",
+        {
+          params: { updateDefinition },
+          ...MOCK_USER_REQOPTS
+        }
+      )
+        .then(response => {
+          // Check service call
+          expect(fetchMock.called()).toEqual(true);
+          const [url, options]: [string, RequestInit] = fetchMock.lastCall("*");
+
+          expect(url).toEqual(
+            "https://services1.arcgis.com/ORG/arcgis/rest/admin/services/FEATURE_SERVICE/FeatureServer/updateDefinition"
+          );
+          expect(options.method).toBe("POST");
+          expect(options.body).toContain("f=json");
+          expect(options.body).toContain(encodeParam("token", "fake-token"));
+          expect(options.body).toContain(
+            encodeParam(
+              "updateDefinition",
+              JSON.stringify(updateDefinition)
+            )
+          );
+
+          // Check response
+          expect(response).toEqual(
+            UpdateServiceDefinitionSuccess
+          );
+          done();
+        })
+        .catch(e => {
+          fail(e);
+        });
+    });
+  }); // auth requests
+});