diff --git a/conformance/runner/go/go.mod b/conformance/runner/go/go.mod
index d89442fb..6120e741 100644
--- a/conformance/runner/go/go.mod
+++ b/conformance/runner/go/go.mod
@@ -1,6 +1,6 @@
 module github.com/basecamp/basecamp-sdk/conformance/runner/go
 
-go 1.26
+go 1.26.3
 
 require github.com/basecamp/basecamp-sdk/go v0.0.0
 
diff --git a/go.work b/go.work
index 758e6395..a2a64112 100644
--- a/go.work
+++ b/go.work
@@ -1,4 +1,4 @@
-go 1.26
+go 1.26.3
 
 use (
 	./conformance/runner/go
diff --git a/go/go.mod b/go/go.mod
index ca78674d..8fb7a0d0 100644
--- a/go/go.mod
+++ b/go/go.mod
@@ -1,6 +1,6 @@
 module github.com/basecamp/basecamp-sdk/go
 
-go 1.26
+go 1.26.3
 
 require (
 	github.com/oapi-codegen/runtime v1.4.0
diff --git a/go/pkg/basecamp/projects.go b/go/pkg/basecamp/projects.go
index 8774c687..d3d1146a 100644
--- a/go/pkg/basecamp/projects.go
+++ b/go/pkg/basecamp/projects.go
@@ -18,6 +18,8 @@ type Project struct {
 	Name           string         `json:"name"`
 	Description    string         `json:"description"`
 	Purpose        string         `json:"purpose"`
+	StartDate      string         `json:"start_date,omitempty"`
+	EndDate        string         `json:"end_date,omitempty"`
 	ClientsEnabled bool           `json:"clients_enabled"`
 	BookmarkURL    string         `json:"bookmark_url"`
 	URL            string         `json:"url"`
@@ -374,6 +376,8 @@ func projectFromGenerated(gp generated.Project) Project {
 		Name:           gp.Name,
 		Description:    gp.Description,
 		Purpose:        gp.Purpose,
+		StartDate:      gp.StartDate,
+		EndDate:        gp.EndDate,
 		ClientsEnabled: gp.ClientsEnabled,
 		BookmarkURL:    gp.BookmarkUrl,
 		URL:            gp.Url,
diff --git a/go/pkg/basecamp/projects_test.go b/go/pkg/basecamp/projects_test.go
index 0cc1d5e3..2872b589 100644
--- a/go/pkg/basecamp/projects_test.go
+++ b/go/pkg/basecamp/projects_test.go
@@ -52,6 +52,12 @@ func TestProject_UnmarshalList(t *testing.T) {
 	if p1.Purpose != "topic" {
 		t.Errorf("expected purpose 'topic', got %q", p1.Purpose)
 	}
+	if p1.StartDate != "2022-01-01" {
+		t.Errorf("expected start_date '2022-01-01', got %q", p1.StartDate)
+	}
+	if p1.EndDate != "2022-04-01" {
+		t.Errorf("expected end_date '2022-04-01', got %q", p1.EndDate)
+	}
 	if p1.ClientCompany != nil {
 		t.Errorf("expected nil ClientCompany for first project")
 	}
@@ -98,6 +104,12 @@ func TestProject_UnmarshalGet(t *testing.T) {
 	if project.Description != "Laptop product launch." {
 		t.Errorf("expected description 'Laptop product launch.', got %q", project.Description)
 	}
+	if project.StartDate != "2022-01-01" {
+		t.Errorf("expected start_date '2022-01-01', got %q", project.StartDate)
+	}
+	if project.EndDate != "2022-04-01" {
+		t.Errorf("expected end_date '2022-04-01', got %q", project.EndDate)
+	}
 	if project.CreatedAt.IsZero() {
 		t.Error("expected non-zero CreatedAt")
 	}
diff --git a/go/pkg/generated/client.gen.go b/go/pkg/generated/client.gen.go
index 9b5334e5..7da5b459 100644
--- a/go/pkg/generated/client.gen.go
+++ b/go/pkg/generated/client.gen.go
@@ -1547,9 +1547,11 @@ type Project struct {
 	CreatedAt   time.Time  `json:"created_at"`
 	Description string     `json:"description,omitempty"`
 	Dock        []DockItem `json:"dock,omitempty"`
+	EndDate     string     `json:"end_date,omitempty"`
 	Id          int64      `json:"id"`
 	Name        string     `json:"name"`
 	Purpose     string     `json:"purpose,omitempty"`
+	StartDate   string     `json:"start_date,omitempty"`
 
 	// Status active|archived|trashed
 	Status    string    `json:"status"`
diff --git a/kotlin/sdk/src/commonMain/kotlin/com/basecamp/sdk/generated/models/Project.kt b/kotlin/sdk/src/commonMain/kotlin/com/basecamp/sdk/generated/models/Project.kt
index fa4f8a36..581755ae 100644
--- a/kotlin/sdk/src/commonMain/kotlin/com/basecamp/sdk/generated/models/Project.kt
+++ b/kotlin/sdk/src/commonMain/kotlin/com/basecamp/sdk/generated/models/Project.kt
@@ -21,6 +21,8 @@ data class Project(
     @SerialName("app_url") val appUrl: String,
     val description: String? = null,
     val purpose: String? = null,
+    @SerialName("start_date") val startDate: String? = null,
+    @SerialName("end_date") val endDate: String? = null,
     @SerialName("clients_enabled") val clientsEnabled: Boolean = false,
     @SerialName("bookmark_url") val bookmarkUrl: String? = null,
     val dock: List<DockItem> = emptyList(),
diff --git a/kotlin/sdk/src/commonTest/kotlin/com/basecamp/sdk/ProjectsServiceTest.kt b/kotlin/sdk/src/commonTest/kotlin/com/basecamp/sdk/ProjectsServiceTest.kt
index fcfa4754..c98d22b9 100644
--- a/kotlin/sdk/src/commonTest/kotlin/com/basecamp/sdk/ProjectsServiceTest.kt
+++ b/kotlin/sdk/src/commonTest/kotlin/com/basecamp/sdk/ProjectsServiceTest.kt
@@ -29,6 +29,7 @@ class ProjectsServiceTest {
     private fun projectJson(id: Long, name: String, description: String? = null) = """{
         "id": $id, "status": "active", "name": "$name",
         "created_at": "2025-01-01T00:00:00Z", "updated_at": "2025-01-01T00:00:00Z",
+        "start_date": "2024-01-01", "end_date": "2024-03-31",
         "url": "https://3.basecampapi.com/12345/projects/$id.json",
         "app_url": "https://3.basecamp.com/12345/projects/$id",
         "dock": []
@@ -108,6 +109,8 @@ class ProjectsServiceTest {
         assertEquals(42L, project.id)
         assertEquals("My Project", project.name)
         assertEquals("A test project", project.description)
+        assertEquals("2024-01-01", project.startDate)
+        assertEquals("2024-03-31", project.endDate)
 
         client.close()
     }
diff --git a/openapi.json b/openapi.json
index 0c6282e8..fa6acfb8 100644
--- a/openapi.json
+++ b/openapi.json
@@ -25032,6 +25032,12 @@
           "purpose": {
             "type": "string"
           },
+          "start_date": {
+            "type": "string"
+          },
+          "end_date": {
+            "type": "string"
+          },
           "clients_enabled": {
             "type": "boolean"
           },
diff --git a/python/src/basecamp/generated/types.py b/python/src/basecamp/generated/types.py
index b2946e5f..52311f3d 100644
--- a/python/src/basecamp/generated/types.py
+++ b/python/src/basecamp/generated/types.py
@@ -1002,9 +1002,11 @@ class Project(TypedDict):
     created_at: str
     description: NotRequired[str]
     dock: NotRequired[list[DockItem]]
+    end_date: NotRequired[str]
     id: int
     name: str
     purpose: NotRequired[str]
+    start_date: NotRequired[str]
     status: str
     updated_at: str
     url: str
diff --git a/python/tests/services/test_projects.py b/python/tests/services/test_projects.py
new file mode 100644
index 00000000..6233b9ba
--- /dev/null
+++ b/python/tests/services/test_projects.py
@@ -0,0 +1,67 @@
+from __future__ import annotations
+
+import httpx
+import respx
+
+from basecamp.client import Client
+
+
+def make_account():
+    client = Client(access_token="test-token")
+    return client, client.for_account("12345")
+
+
+class TestProjects:
+    @respx.mock
+    def test_get_project_includes_schedule_dates(self):
+        respx.get("https://3.basecampapi.com/12345/projects/42").mock(
+            return_value=httpx.Response(
+                200,
+                json={
+                    "id": 42,
+                    "name": "My Project",
+                    "status": "active",
+                    "start_date": "2024-01-01",
+                    "end_date": "2024-03-31",
+                    "created_at": "2024-01-15T10:00:00Z",
+                    "updated_at": "2024-01-15T10:00:00Z",
+                    "url": "https://3.basecampapi.com/12345/projects/42.json",
+                    "app_url": "https://3.basecamp.com/12345/projects/42",
+                },
+            )
+        )
+
+        client, account = make_account()
+        project = account.projects.get(project_id=42)
+        client.close()
+
+        assert project["start_date"] == "2024-01-01"
+        assert project["end_date"] == "2024-03-31"
+
+    @respx.mock
+    def test_list_projects_includes_schedule_dates(self):
+        respx.get("https://3.basecampapi.com/12345/projects.json").mock(
+            return_value=httpx.Response(
+                200,
+                json=[
+                    {
+                        "id": 1,
+                        "name": "Project A",
+                        "status": "active",
+                        "start_date": "2024-01-01",
+                        "end_date": "2024-03-31",
+                        "created_at": "2024-01-15T10:00:00Z",
+                        "updated_at": "2024-01-15T10:00:00Z",
+                        "url": "https://3.basecampapi.com/12345/projects/1.json",
+                        "app_url": "https://3.basecamp.com/12345/projects/1",
+                    }
+                ],
+            )
+        )
+
+        client, account = make_account()
+        projects = account.projects.list()
+        client.close()
+
+        assert projects[0]["start_date"] == "2024-01-01"
+        assert projects[0]["end_date"] == "2024-03-31"
diff --git a/ruby/lib/basecamp/generated/metadata.json b/ruby/lib/basecamp/generated/metadata.json
index d5cd3625..313f2758 100644
--- a/ruby/lib/basecamp/generated/metadata.json
+++ b/ruby/lib/basecamp/generated/metadata.json
@@ -1,7 +1,7 @@
 {
   "$schema": "https://basecamp.com/schemas/sdk-metadata.json",
   "version": "1.0.0",
-  "generated": "2026-04-29T18:03:49Z",
+  "generated": "2026-05-07T21:00:08Z",
   "operations": {
     "GetAccount": {
       "retry": {
diff --git a/ruby/lib/basecamp/generated/types.rb b/ruby/lib/basecamp/generated/types.rb
index 8cc6ed85..aff2b040 100644
--- a/ruby/lib/basecamp/generated/types.rb
+++ b/ruby/lib/basecamp/generated/types.rb
@@ -1,7 +1,7 @@
 # frozen_string_literal: true
 
 # Auto-generated from OpenAPI spec. Do not edit manually.
-# Generated: 2026-04-29T18:03:49Z
+# Generated: 2026-05-07T21:00:08Z
 
 require "json"
 require "time"
@@ -2427,7 +2427,7 @@ def to_json(*args)
     # Project
     class Project
       include TypeHelpers
-      attr_accessor :app_url, :created_at, :id, :name, :status, :updated_at, :url, :bookmark_url, :bookmarked, :client_company, :clients_enabled, :clientside, :description, :dock, :purpose
+      attr_accessor :app_url, :created_at, :id, :name, :status, :updated_at, :url, :bookmark_url, :bookmarked, :client_company, :clients_enabled, :clientside, :description, :dock, :end_date, :purpose, :start_date
 
       # @return [Array<Symbol>]
       def self.required_fields
@@ -2449,7 +2449,9 @@ def initialize(data = {})
         @clientside = parse_type(data["clientside"], "ClientSide")
         @description = data["description"]
         @dock = parse_array(data["dock"], "DockItem")
+        @end_date = data["end_date"]
         @purpose = data["purpose"]
+        @start_date = data["start_date"]
       end
 
       def to_h
@@ -2468,7 +2470,9 @@ def to_h
           "clientside" => @clientside,
           "description" => @description,
           "dock" => @dock,
+          "end_date" => @end_date,
           "purpose" => @purpose,
+          "start_date" => @start_date,
         }.compact
       end
 
diff --git a/ruby/test/basecamp/services/projects_service_test.rb b/ruby/test/basecamp/services/projects_service_test.rb
index 9b7bbffc..efc925ad 100644
--- a/ruby/test/basecamp/services/projects_service_test.rb
+++ b/ruby/test/basecamp/services/projects_service_test.rb
@@ -20,7 +20,9 @@ def sample_project(id: 123, name: "Test Project")
       "id" => id,
       "name" => name,
       "description" => "A test project",
-      "status" => "active"
+      "status" => "active",
+      "start_date" => "2024-01-01",
+      "end_date" => "2024-03-31"
     }
   end
 
@@ -52,6 +54,8 @@ def test_get_project
 
     assert_equal 123, project["id"]
     assert_equal "Test Project", project["name"]
+    assert_equal "2024-01-01", project["start_date"]
+    assert_equal "2024-03-31", project["end_date"]
   end
 
   def test_create_project
diff --git a/spec/basecamp.smithy b/spec/basecamp.smithy
index f1db530b..ebf2d636 100644
--- a/spec/basecamp.smithy
+++ b/spec/basecamp.smithy
@@ -565,6 +565,8 @@ structure Project {
   name: ProjectName
   description: ProjectDescription
   purpose: String
+  start_date: ISO8601Date
+  end_date: ISO8601Date
   clients_enabled: Boolean
   bookmark_url: String
   @required
diff --git a/spec/fixtures/projects/README.md b/spec/fixtures/projects/README.md
index 0f68cc94..43e2ded2 100644
--- a/spec/fixtures/projects/README.md
+++ b/spec/fixtures/projects/README.md
@@ -37,7 +37,7 @@ JSON fixtures extracted from the canonical projects docs in `basecamp/bc3/doc/ap
 
 ## Notes
 
-- list.json includes a project with `client_company` and `clientside` fields (id: 2085958500)
-- get.json is a basic project without client fields
+- get.json includes a scheduled project with `start_date` and `end_date`
+- list.json includes one scheduled project and one project with `client_company` and `clientside` fields (id: 2085958500)
 - DockItem.position can be null when enabled=false
 - All timestamps are ISO8601 format
diff --git a/spec/fixtures/projects/get.json b/spec/fixtures/projects/get.json
index 4c0e1e4b..d9e18198 100644
--- a/spec/fixtures/projects/get.json
+++ b/spec/fixtures/projects/get.json
@@ -6,6 +6,8 @@
   "name": "The Leto Laptop",
   "description": "Laptop product launch.",
   "purpose": "topic",
+  "start_date": "2022-01-01",
+  "end_date": "2022-04-01",
   "clients_enabled": false,
   "bookmark_url": "https://3.basecampapi.com/195539477/my/bookmarks/BAh7CEkiCGdpZAY6BkVUSSIrZ2lkOi8vYmMzL0J1Y2tldC8yMDg1OTU4NDk5P2V4cGlyZXNfaW4GOwBUSSIMcHVycG9zZQY7AFRJIg1yZWFkYWJsZQY7AFRJIg9leHBpcmVzX2F0BjsAVDA=--691d627098347705738640552798539681dcd3b6.json",
   "url": "https://3.basecampapi.com/195539477/projects/2085958499.json",
diff --git a/spec/fixtures/projects/list.json b/spec/fixtures/projects/list.json
index ee486f4c..0f13a574 100644
--- a/spec/fixtures/projects/list.json
+++ b/spec/fixtures/projects/list.json
@@ -7,6 +7,8 @@
     "name": "The Leto Laptop",
     "description": "Laptop product launch.",
     "purpose": "topic",
+    "start_date": "2022-01-01",
+    "end_date": "2022-04-01",
     "clients_enabled": false,
     "bookmark_url": "https://3.basecampapi.com/195539477/my/bookmarks/BAh7CEkiCGdpZAY6BkVUSSIrZ2lkOi8vYmMzL0J1Y2tldC8yMDg1OTU4NDk5P2V4cGlyZXNfaW4GOwBUSSIMcHVycG9zZQY7AFRJIg1yZWFkYWJsZQY7AFRJIg9leHBpcmVzX2F0BjsAVDA=--691d627098347705738640552798539681dcd3b6.json",
     "url": "https://3.basecampapi.com/195539477/projects/2085958499.json",
diff --git a/swift/Sources/Basecamp/Generated/Models/Project.swift b/swift/Sources/Basecamp/Generated/Models/Project.swift
index da45c83d..f49afc3c 100644
--- a/swift/Sources/Basecamp/Generated/Models/Project.swift
+++ b/swift/Sources/Basecamp/Generated/Models/Project.swift
@@ -16,7 +16,9 @@ public struct Project: Codable, Sendable {
     public var clientside: ClientSide?
     public var description: String?
     public var dock: [DockItem]?
+    public var endDate: String?
     public var purpose: String?
+    public var startDate: String?
 
     public init(
         appUrl: String,
@@ -33,7 +35,9 @@ public struct Project: Codable, Sendable {
         clientside: ClientSide? = nil,
         description: String? = nil,
         dock: [DockItem]? = nil,
-        purpose: String? = nil
+        endDate: String? = nil,
+        purpose: String? = nil,
+        startDate: String? = nil
     ) {
         self.appUrl = appUrl
         self.createdAt = createdAt
@@ -49,6 +53,8 @@ public struct Project: Codable, Sendable {
         self.clientside = clientside
         self.description = description
         self.dock = dock
+        self.endDate = endDate
         self.purpose = purpose
+        self.startDate = startDate
     }
 }
diff --git a/swift/Tests/BasecampTests/GeneratedServiceTests.swift b/swift/Tests/BasecampTests/GeneratedServiceTests.swift
index d893454a..84a7b240 100644
--- a/swift/Tests/BasecampTests/GeneratedServiceTests.swift
+++ b/swift/Tests/BasecampTests/GeneratedServiceTests.swift
@@ -13,6 +13,7 @@ final class GeneratedServiceTests: XCTestCase {
             "id": 42, "name": "My Project", "status": "active",
             "app_url": "https://3.basecamp.com/1/projects/42", "url": "https://3.basecampapi.com/1/projects/42.json",
             "created_at": "2026-01-01T00:00:00Z", "updated_at": "2026-01-01T00:00:00Z",
+            "start_date": "2024-01-01", "end_date": "2024-03-31",
         ]
         let data = try JSONSerialization.data(withJSONObject: json)
 
@@ -23,6 +24,8 @@ final class GeneratedServiceTests: XCTestCase {
         XCTAssertEqual(project.id, 42)
         XCTAssertEqual(project.name, "My Project")
         XCTAssertEqual(project.status, "active")
+        XCTAssertEqual(project.startDate, "2024-01-01")
+        XCTAssertEqual(project.endDate, "2024-03-31")
 
         // Verify request was sent to the correct path
         let lastURL = transport.lastRequest!.request.url!.absoluteString
@@ -79,7 +82,8 @@ final class GeneratedServiceTests: XCTestCase {
         let projects: [[String: Any]] = [
             ["id": 1, "name": "Project A", "status": "active",
              "app_url": "https://3.basecamp.com/1/projects/1", "url": "https://3.basecampapi.com/1/projects/1.json",
-             "created_at": "2026-01-01T00:00:00Z", "updated_at": "2026-01-01T00:00:00Z"],
+             "created_at": "2026-01-01T00:00:00Z", "updated_at": "2026-01-01T00:00:00Z",
+             "start_date": "2024-01-01", "end_date": "2024-03-31"],
             ["id": 2, "name": "Project B", "status": "active",
              "app_url": "https://3.basecamp.com/1/projects/2", "url": "https://3.basecampapi.com/1/projects/2.json",
              "created_at": "2026-01-01T00:00:00Z", "updated_at": "2026-01-01T00:00:00Z"],
@@ -93,6 +97,7 @@ final class GeneratedServiceTests: XCTestCase {
         let result = try await account.projects.list()
         XCTAssertEqual(result.count, 2)
         XCTAssertEqual(result[0].id, 1)
+        XCTAssertEqual(result[0].startDate, "2024-01-01")
         XCTAssertEqual(result[1].name, "Project B")
         XCTAssertEqual(result.meta.totalCount, 2)
     }
diff --git a/typescript/src/generated/metadata.json b/typescript/src/generated/metadata.json
index 940586b0..1b2f7732 100644
--- a/typescript/src/generated/metadata.json
+++ b/typescript/src/generated/metadata.json
@@ -1,7 +1,7 @@
 {
   "$schema": "https://basecamp.com/schemas/sdk-metadata.json",
   "version": "1.0.0",
-  "generated": "2026-04-29T18:03:48.821Z",
+  "generated": "2026-05-07T21:00:07.713Z",
   "operations": {
     "GetAccount": {
       "retry": {
diff --git a/typescript/src/generated/openapi-stripped.json b/typescript/src/generated/openapi-stripped.json
index 496f978d..f647dab7 100644
--- a/typescript/src/generated/openapi-stripped.json
+++ b/typescript/src/generated/openapi-stripped.json
@@ -22708,6 +22708,12 @@
           "purpose": {
             "type": "string"
           },
+          "start_date": {
+            "type": "string"
+          },
+          "end_date": {
+            "type": "string"
+          },
           "clients_enabled": {
             "type": "boolean"
           },
diff --git a/typescript/src/generated/schema.d.ts b/typescript/src/generated/schema.d.ts
index ad185afd..7c36fb33 100644
--- a/typescript/src/generated/schema.d.ts
+++ b/typescript/src/generated/schema.d.ts
@@ -3678,6 +3678,8 @@ export interface components {
             name: string;
             description?: string;
             purpose?: string;
+            start_date?: string;
+            end_date?: string;
             clients_enabled?: boolean;
             bookmark_url?: string;
             url: string;
diff --git a/typescript/tests/services/projects.test.ts b/typescript/tests/services/projects.test.ts
index c6dfb358..688eb429 100644
--- a/typescript/tests/services/projects.test.ts
+++ b/typescript/tests/services/projects.test.ts
@@ -15,6 +15,8 @@ const sampleProject = (id = 1) => ({
   name: "My Project",
   description: "<p>A cool project</p>",
   status: "active",
+  start_date: "2024-01-01",
+  end_date: "2024-03-31",
   created_at: "2024-01-15T10:00:00Z",
   updated_at: "2024-01-15T10:00:00Z",
 });
@@ -41,6 +43,7 @@ describe("ProjectsService", () => {
       const projects = await client.projects.list();
       expect(projects).toHaveLength(2);
       expect(projects[0]!.id).toBe(1);
+      expect(projects[0]!.start_date).toBe("2024-01-01");
       expect(projects[1]!.id).toBe(2);
     });
 
@@ -69,6 +72,8 @@ describe("ProjectsService", () => {
       const project = await client.projects.get(projectId);
       expect(project.id).toBe(projectId);
       expect(project.name).toBe("My Project");
+      expect(project.start_date).toBe("2024-01-01");
+      expect(project.end_date).toBe("2024-03-31");
     });
 
     it("should throw not_found for missing project", async () => {