diff --git a/src/services/index.ts b/src/services/index.ts
new file mode 100644
index 0000000..836b90d
--- /dev/null
+++ b/src/services/index.ts
@@ -0,0 +1,9 @@
+/**
+ * Domain Services Barrel Export.
+ */
+
+export * from "./helper.ts";
+export * from "./projects.ts";
+export * from "./work-packages.ts";
+export * from "./queries.ts";
+export * from "./metadata.ts";
diff --git a/src/services/metadata.ts b/src/services/metadata.ts
new file mode 100644
index 0000000..4f64eea
--- /dev/null
+++ b/src/services/metadata.ts
@@ -0,0 +1,88 @@
+/**
+ * Metadata & Taxonomies Domain Service.
+ */
+
+import type { OpenProjectClient } from "../client/api-client.ts";
+import {
+  normalizePriority,
+  normalizeStatus,
+  normalizeType,
+  normalizeUser,
+  unpackCollection,
+} from "../client/hal-parser.ts";
+import type {
+  HalCollection,
+  HalResource,
+  PaginatedResult,
+  PriorityItem,
+  StatusItem,
+  TypeItem,
+  UserItem,
+} from "../client/types.ts";
+import { resolveClient } from "./helper.ts";
+
+export interface ListTypesParams {
+  projectId?: number | string;
+}
+
+export interface ListUsersParams {
+  pageSize?: number;
+  offset?: number;
+  status?: string;
+}
+
+/**
+ * Lists all work package statuses available in the system.
+ */
+export async function listStatuses(
+  client?: OpenProjectClient
+): Promise<StatusItem[]> {
+  const opClient = resolveClient(client);
+  const response = await opClient.get<HalCollection<HalResource>>("statuses");
+  const unpacked = unpackCollection(response, normalizeStatus);
+  return unpacked.items;
+}
+
+/**
+ * Lists work package types, optionally filtered to those enabled for a specific project.
+ */
+export async function listTypes(
+  params?: ListTypesParams,
+  client?: OpenProjectClient
+): Promise<TypeItem[]> {
+  const opClient = resolveClient(client);
+  const path = params?.projectId !== undefined ? `projects/${params.projectId}/types` : "types";
+  const response = await opClient.get<HalCollection<HalResource>>(path);
+  const unpacked = unpackCollection(response, normalizeType);
+  return unpacked.items;
+}
+
+/**
+ * Lists issue priority levels configured in the system.
+ */
+export async function listPriorities(
+  client?: OpenProjectClient
+): Promise<PriorityItem[]> {
+  const opClient = resolveClient(client);
+  const response = await opClient.get<HalCollection<HalResource>>("priorities");
+  const unpacked = unpackCollection(response, normalizePriority);
+  return unpacked.items;
+}
+
+/**
+ * Lists users in the OpenProject instance with pagination.
+ */
+export async function listUsers(
+  params?: ListUsersParams,
+  client?: OpenProjectClient
+): Promise<PaginatedResult<UserItem>> {
+  const opClient = resolveClient(client);
+  const query: Record<string, string | number | boolean | undefined> = {};
+
+  if (params?.pageSize !== undefined) query.pageSize = params.pageSize;
+  if (params?.offset !== undefined) query.offset = params.offset;
+  if (params?.status !== undefined) query.status = params.status;
+
+  const response = await opClient.get<HalCollection<HalResource>>("users", query);
+  return unpackCollection(response, normalizeUser);
+}
diff --git a/tests/services.test.ts b/tests/services.test.ts
index 980cc8f..c045861 100644
--- a/tests/services.test.ts
+++ b/tests/services.test.ts
@@ -7,6 +7,13 @@ import {
   searchWorkPackages,
 } from "../src/services/work-packages.ts";
 import { listQueries, getQuery, getQueryResults } from "../src/services/queries.ts";
+import {
+  listStatuses,
+  listTypes,
+  listPriorities,
+  listUsers,
+} from "../src/services/metadata.ts";
+import * as domainServices from "../src/services/index.ts";
 import { OpenProjectClient } from "../src/client/api-client.ts";
 import { runWithContext, type RequestContext } from "../src/context.ts";
 
@@ -383,3 +390,129 @@ describe("Queries Service", () => {
     expect(result.items[0].subject).toBe("Implement MCP Server Core Protocol");
   });
 });
+
+describe("Metadata Service", () => {
+  test("listStatuses retrieves and unpacks status items", async () => {
+    const mockFetch = async () => {
+      return new Response(
+        JSON.stringify({
+          _type: "Collection",
+          _embedded: {
+            elements: [
+              { id: 1, name: "New", isClosed: false, isDefault: true },
+              { id: 2, name: "Closed", isClosed: true, isDefault: false },
+            ],
+          },
+        }),
+        { headers: { "Content-Type": "application/hal+json" } }
+      );
+    };
+
+    const client = new OpenProjectClient({
+      baseUrl: "http://example.com",
+      apiKey: "test-key",
+      fetchFn: mockFetch,
+    });
+
+    const statuses = await listStatuses(client);
+    expect(statuses.length).toBe(2);
+    expect(statuses[0].name).toBe("New");
+    expect(statuses[0].isClosed).toBe(false);
+    expect(statuses[1].isClosed).toBe(true);
+  });
+
+  test("listTypes scopes to project when projectId is provided", async () => {
+    let requestedUrl = "";
+    const mockFetch = async (input: string | URL | Request) => {
+      requestedUrl = String(input);
+      return new Response(
+        JSON.stringify({
+          _type: "Collection",
+          _embedded: {
+            elements: [{ id: 1, name: "Task", isMilestone: false }],
+          },
+        }),
+        { headers: { "Content-Type": "application/hal+json" } }
+      );
+    };
+
+    const client = new OpenProjectClient({
+      baseUrl: "http://example.com",
+      apiKey: "test-key",
+      fetchFn: mockFetch,
+    });
+
+    const types = await listTypes({ projectId: 4 }, client);
+    expect(requestedUrl).toContain("/api/v3/projects/4/types");
+    expect(types[0].name).toBe("Task");
+  });
+
+  test("listPriorities retrieves priority items", async () => {
+    const mockFetch = async () => {
+      return new Response(
+        JSON.stringify({
+          _type: "Collection",
+          _embedded: {
+            elements: [{ id: 8, name: "High", isActive: true }],
+          },
+        }),
+        { headers: { "Content-Type": "application/hal+json" } }
+      );
+    };
+
+    const client = new OpenProjectClient({
+      baseUrl: "http://example.com",
+      apiKey: "test-key",
+      fetchFn: mockFetch,
+    });
+
+    const priorities = await listPriorities(client);
+    expect(priorities[0].name).toBe("High");
+  });
+
+  test("listUsers returns paginated UserItem list", async () => {
+    let requestedUrl = "";
+    const mockFetch = async (input: string | URL | Request) => {
+      requestedUrl = String(input);
+      return new Response(
+        JSON.stringify({
+          _type: "Collection",
+          total: 1,
+          count: 1,
+          pageSize: 25,
+          offset: 1,
+          _embedded: {
+            elements: [{ id: 1, name: "Admin User", login: "admin", admin: true }],
+          },
+        }),
+        { headers: { "Content-Type": "application/hal+json" } }
+      );
+    };
+
+    const client = new OpenProjectClient({
+      baseUrl: "http://example.com",
+      apiKey: "test-key",
+      fetchFn: mockFetch,
+    });
+
+    const users = await listUsers({ pageSize: 25, offset: 1 }, client);
+    expect(requestedUrl).toContain("/api/v3/users");
+    expect(users.items[0].login).toBe("admin");
+    expect(users.items[0].admin).toBe(true);
+  });
+
+  test("src/services/index.ts exports all services properly", () => {
+    expect(typeof domainServices.listProjects).toBe("function");
+    expect(typeof domainServices.getProject).toBe("function");
+    expect(typeof domainServices.getProjectSchema).toBe("function");
+    expect(typeof domainServices.listWorkPackages).toBe("function");
+    expect(typeof domainServices.getWorkPackage).toBe("function");
+    expect(typeof domainServices.listQueries).toBe("function");
+    expect(typeof domainServices.getQuery).toBe("function");
+    expect(typeof domainServices.listStatuses).toBe("function");
+    expect(typeof domainServices.listTypes).toBe("function");
+    expect(typeof domainServices.listPriorities).toBe("function");
+    expect(typeof domainServices.listUsers).toBe("function");
+  });
+});
+