diff --git a/src/services/projects.ts b/src/services/projects.ts
new file mode 100644
index 0000000..76a6dbf
--- /dev/null
+++ b/src/services/projects.ts
@@ -0,0 +1,69 @@
+/**
+ * Projects Domain Service.
+ */
+
+import type { OpenProjectClient } from "../client/api-client.ts";
+import {
+  normalizeProject,
+  normalizeProjectSummary,
+  unpackCollection,
+} from "../client/hal-parser.ts";
+import type {
+  FilterElement,
+  HalCollection,
+  HalResource,
+  PaginatedResult,
+  ProjectDetail,
+  ProjectSummary,
+} from "../client/types.ts";
+import { resolveClient } from "./helper.ts";
+
+export interface ListProjectsParams {
+  pageSize?: number;
+  offset?: number;
+  sortBy?: string;
+  filters?: FilterElement[];
+}
+
+/**
+ * Lists projects accessible to the authenticated user.
+ */
+export async function listProjects(
+  params?: ListProjectsParams,
+  client?: OpenProjectClient
+): Promise<PaginatedResult<ProjectSummary>> {
+  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?.sortBy !== undefined) query.sortBy = params.sortBy;
+  if (params?.filters && params.filters.length > 0) {
+    query.filters = JSON.stringify(params.filters);
+  }
+
+  const response = await opClient.get<HalCollection<HalResource>>("projects", query);
+  return unpackCollection(response, normalizeProjectSummary);
+}
+
+/**
+ * Retrieves a single project by its numeric ID or string identifier.
+ */
+export async function getProject(
+  idOrIdentifier: number | string,
+  client?: OpenProjectClient
+): Promise<ProjectDetail> {
+  const opClient = resolveClient(client);
+  const response = await opClient.get<HalResource>(`projects/${idOrIdentifier}`);
+  return normalizeProject(response);
+}
+
+/**
+ * Retrieves the schema definition for projects.
+ */
+export async function getProjectSchema(
+  client?: OpenProjectClient
+): Promise<Record<string, unknown>> {
+  const opClient = resolveClient(client);
+  return opClient.get<Record<string, unknown>>("projects/schema");
+}
diff --git a/tests/services.test.ts b/tests/services.test.ts
index c51e73a..085363c 100644
--- a/tests/services.test.ts
+++ b/tests/services.test.ts
@@ -1,5 +1,6 @@
 import { describe, expect, test } from "bun:test";
 import { resolveClient } from "../src/services/helper.ts";
+import { listProjects, getProject, getProjectSchema } from "../src/services/projects.ts";
 import { OpenProjectClient } from "../src/client/api-client.ts";
 import { runWithContext, type RequestContext } from "../src/context.ts";
 
@@ -33,3 +34,96 @@ describe("Domain Services Helper", () => {
     expect(() => resolveClient()).toThrow("No active RequestContext found");
   });
 });
+
+describe("Projects Service", () => {
+  const sampleProjectHal = {
+    _type: "Project",
+    id: 4,
+    identifier: "mcp-test-project",
+    name: "MCP Test Project",
+    active: true,
+    public: true,
+    description: { format: "markdown", raw: "Dedicated test project" },
+    _links: {
+      self: { href: "/api/v3/projects/4", title: "MCP Test Project" },
+      parent: { href: "/api/v3/projects/1", title: "Parent Project" },
+    },
+  };
+
+  test("listProjects sends correct parameters and returns paginated ProjectSummary items", 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: 10,
+          offset: 1,
+          _embedded: {
+            elements: [sampleProjectHal],
+          },
+        }),
+        { headers: { "Content-Type": "application/hal+json" } }
+      );
+    };
+
+    const client = new OpenProjectClient({
+      baseUrl: "http://example.com",
+      apiKey: "test-key",
+      fetchFn: mockFetch,
+    });
+
+    const result = await listProjects({ pageSize: 10, offset: 1, sortBy: '[["name","asc"]]' }, client);
+
+    expect(requestedUrl).toContain("/api/v3/projects");
+    expect(requestedUrl).toContain("pageSize=10");
+    expect(requestedUrl).toContain("offset=1");
+    expect(requestedUrl).toContain("sortBy=");
+    expect(result.total).toBe(1);
+    expect(result.items[0].id).toBe(4);
+    expect(result.items[0].identifier).toBe("mcp-test-project");
+    expect(result.items[0].name).toBe("MCP Test Project");
+  });
+
+  test("getProject retrieves project detail by id or identifier", async () => {
+    let requestedUrl = "";
+    const mockFetch = async (input: string | URL | Request) => {
+      requestedUrl = String(input);
+      return new Response(JSON.stringify(sampleProjectHal), {
+        headers: { "Content-Type": "application/hal+json" },
+      });
+    };
+
+    const client = new OpenProjectClient({
+      baseUrl: "http://example.com",
+      apiKey: "test-key",
+      fetchFn: mockFetch,
+    });
+
+    const result = await getProject("mcp-test-project", client);
+    expect(requestedUrl).toContain("/api/v3/projects/mcp-test-project");
+    expect(result.id).toBe(4);
+    expect(result.parentId).toBe(1);
+    expect(result.parentName).toBe("Parent Project");
+  });
+
+  test("getProjectSchema retrieves project schema definition", async () => {
+    const mockFetch = async () => {
+      return new Response(JSON.stringify({ _type: "Schema", name: { type: "String" } }), {
+        headers: { "Content-Type": "application/json" },
+      });
+    };
+
+    const client = new OpenProjectClient({
+      baseUrl: "http://example.com",
+      apiKey: "test-key",
+      fetchFn: mockFetch,
+    });
+
+    const result = await getProjectSchema(client);
+    expect(result._type).toBe("Schema");
+  });
+});
+