diff --git a/IMPLEMENTATION_PLAN.md b/IMPLEMENTATION_PLAN.md
index 6538371..be3a287 100644
--- a/IMPLEMENTATION_PLAN.md
+++ b/IMPLEMENTATION_PLAN.md
@@ -46,7 +46,7 @@ This file is maintained by Ralph. Run `./ralph-sandbox.sh plan 3` to generate ta
 |------|--------|-------|
 | Dashboard (`/`) | **COMPLETE** | Wired with /api/today, DecisionCard, DataPanel, NutritionPanel, OverrideToggles |
 | Login (`/login`) | **COMPLETE** | Email/password form with auth, error handling, loading states |
-| Settings (`/settings`) | Placeholder | Needs form implementation |
+| Settings (`/settings`) | **COMPLETE** | Form with cycleLength, notificationTime, timezone |
 | Settings/Garmin (`/settings/garmin`) | Placeholder | Needs token management UI |
 | Calendar (`/calendar`) | Placeholder | Needs MonthView integration |
 | History (`/history`) | Placeholder | Needs list/pagination implementation |
@@ -374,12 +374,12 @@ Full feature set for production use.
 - **Why:** Users want to see their training history
 - **Depends On:** P0.1, P0.2
 
-### P2.9: Settings Page Implementation
-- [ ] User profile management UI
+### P2.9: Settings Page Implementation ✅ COMPLETE
+- [x] User profile management UI
 - **Files:**
-  - `src/app/settings/page.tsx` - Form for cycleLength, notificationTime, timezone
+  - `src/app/settings/page.tsx` - Form for cycleLength, notificationTime, timezone with validation, loading states, error handling
 - **Tests:**
-  - E2E test: settings update and persist
+  - `src/app/settings/page.test.tsx` - 24 tests covering rendering, data loading, form submission, validation, error handling
 - **Why:** Users need to configure their preferences
 - **Depends On:** P0.4, P1.1
 
@@ -614,6 +614,7 @@ P2.14 Mini calendar
 ### Pages
 - [x] **Login Page** - Email/password form with PocketBase auth, error handling, loading states, redirect, 14 tests (P1.6)
 - [x] **Dashboard Page** - Complete daily interface with /api/today integration, DecisionCard, DataPanel, NutritionPanel, OverrideToggles, 23 tests (P1.7)
+- [x] **Settings Page** - Form for cycleLength, notificationTime, timezone with validation, loading states, error handling, 24 tests (P2.9)
 
 ### Test Infrastructure
 - [x] **test-setup.ts** - Global test setup with @testing-library/jest-dom matchers and cleanup
diff --git a/src/app/settings/page.test.tsx b/src/app/settings/page.test.tsx
new file mode 100644
index 0000000..6873d50
--- /dev/null
+++ b/src/app/settings/page.test.tsx
@@ -0,0 +1,475 @@
+// ABOUTME: Unit tests for the Settings page component.
+// ABOUTME: Tests form rendering, data loading, validation, and save flow.
+import { fireEvent, render, screen, waitFor } from "@testing-library/react";
+import { beforeEach, describe, expect, it, vi } from "vitest";
+
+// Mock next/navigation
+const mockPush = vi.fn();
+vi.mock("next/navigation", () => ({
+  useRouter: () => ({
+    push: mockPush,
+  }),
+}));
+
+// Mock fetch
+const mockFetch = vi.fn();
+global.fetch = mockFetch;
+
+import SettingsPage from "./page";
+
+describe("SettingsPage", () => {
+  const mockUser = {
+    id: "user123",
+    email: "test@example.com",
+    cycleLength: 28,
+    notificationTime: "08:00",
+    timezone: "America/New_York",
+    garminConnected: false,
+    activeOverrides: [],
+    lastPeriodDate: "2024-01-01",
+  };
+
+  beforeEach(() => {
+    vi.clearAllMocks();
+    mockFetch.mockResolvedValue({
+      ok: true,
+      json: () => Promise.resolve(mockUser),
+    });
+  });
+
+  describe("rendering", () => {
+    it("renders the settings heading", async () => {
+      render(<SettingsPage />);
+
+      await waitFor(() => {
+        expect(
+          screen.getByRole("heading", { name: /settings/i }),
+        ).toBeInTheDocument();
+      });
+    });
+
+    it("renders cycle length input", async () => {
+      render(<SettingsPage />);
+
+      await waitFor(() => {
+        expect(screen.getByLabelText(/cycle length/i)).toBeInTheDocument();
+      });
+    });
+
+    it("renders notification time input", async () => {
+      render(<SettingsPage />);
+
+      await waitFor(() => {
+        expect(screen.getByLabelText(/notification time/i)).toBeInTheDocument();
+      });
+    });
+
+    it("renders timezone input", async () => {
+      render(<SettingsPage />);
+
+      await waitFor(() => {
+        expect(screen.getByLabelText(/timezone/i)).toBeInTheDocument();
+      });
+    });
+
+    it("renders a save button", async () => {
+      render(<SettingsPage />);
+
+      await waitFor(() => {
+        expect(
+          screen.getByRole("button", { name: /save/i }),
+        ).toBeInTheDocument();
+      });
+    });
+
+    it("renders a back link to dashboard", async () => {
+      render(<SettingsPage />);
+
+      await waitFor(() => {
+        expect(screen.getByRole("link", { name: /back/i })).toHaveAttribute(
+          "href",
+          "/",
+        );
+      });
+    });
+
+    it("displays email as read-only", async () => {
+      render(<SettingsPage />);
+
+      await waitFor(() => {
+        expect(screen.getByText("test@example.com")).toBeInTheDocument();
+      });
+    });
+  });
+
+  describe("data loading", () => {
+    it("fetches user data on mount", async () => {
+      render(<SettingsPage />);
+
+      await waitFor(() => {
+        expect(mockFetch).toHaveBeenCalledWith("/api/user");
+      });
+    });
+
+    it("shows loading state while fetching", async () => {
+      // Create a promise that we can control
+      let resolveUser: (value: unknown) => void = () => {};
+      const userPromise = new Promise((resolve) => {
+        resolveUser = resolve;
+      });
+      mockFetch.mockReturnValue({
+        ok: true,
+        json: () => userPromise,
+      });
+
+      render(<SettingsPage />);
+
+      expect(screen.getByText(/loading/i)).toBeInTheDocument();
+
+      resolveUser(mockUser);
+
+      await waitFor(() => {
+        expect(screen.queryByText(/loading/i)).not.toBeInTheDocument();
+      });
+    });
+
+    it("pre-fills form with current user values", async () => {
+      render(<SettingsPage />);
+
+      await waitFor(() => {
+        expect(screen.getByLabelText(/cycle length/i)).toHaveValue(28);
+        expect(screen.getByLabelText(/notification time/i)).toHaveValue(
+          "08:00",
+        );
+        expect(screen.getByLabelText(/timezone/i)).toHaveValue(
+          "America/New_York",
+        );
+      });
+    });
+
+    it("shows error if fetching fails", async () => {
+      mockFetch.mockResolvedValueOnce({
+        ok: false,
+        json: () => Promise.resolve({ error: "Failed to fetch user" }),
+      });
+
+      render(<SettingsPage />);
+
+      await waitFor(() => {
+        expect(screen.getByRole("alert")).toBeInTheDocument();
+        expect(screen.getByText(/failed to fetch user/i)).toBeInTheDocument();
+      });
+    });
+  });
+
+  describe("form submission", () => {
+    it("calls PATCH /api/user with updated values on save", async () => {
+      mockFetch
+        .mockResolvedValueOnce({
+          ok: true,
+          json: () => Promise.resolve(mockUser),
+        })
+        .mockResolvedValueOnce({
+          ok: true,
+          json: () => Promise.resolve({ ...mockUser, cycleLength: 30 }),
+        });
+
+      render(<SettingsPage />);
+
+      await waitFor(() => {
+        expect(screen.getByLabelText(/cycle length/i)).toBeInTheDocument();
+      });
+
+      const cycleLengthInput = screen.getByLabelText(/cycle length/i);
+      fireEvent.change(cycleLengthInput, { target: { value: "30" } });
+
+      const saveButton = screen.getByRole("button", { name: /save/i });
+      fireEvent.click(saveButton);
+
+      await waitFor(() => {
+        expect(mockFetch).toHaveBeenCalledWith("/api/user", {
+          method: "PATCH",
+          headers: { "Content-Type": "application/json" },
+          body: JSON.stringify({
+            cycleLength: 30,
+            notificationTime: "08:00",
+            timezone: "America/New_York",
+          }),
+        });
+      });
+    });
+
+    it("shows loading state while saving", async () => {
+      let resolveSave: (value: unknown) => void = () => {};
+      const savePromise = new Promise((resolve) => {
+        resolveSave = resolve;
+      });
+
+      mockFetch
+        .mockResolvedValueOnce({
+          ok: true,
+          json: () => Promise.resolve(mockUser),
+        })
+        .mockReturnValueOnce({
+          ok: true,
+          json: () => savePromise,
+        });
+
+      render(<SettingsPage />);
+
+      await waitFor(() => {
+        expect(screen.getByLabelText(/cycle length/i)).toBeInTheDocument();
+      });
+
+      const saveButton = screen.getByRole("button", { name: /save/i });
+      fireEvent.click(saveButton);
+
+      await waitFor(() => {
+        expect(
+          screen.getByRole("button", { name: /saving/i }),
+        ).toBeInTheDocument();
+      });
+
+      resolveSave(mockUser);
+    });
+
+    it("disables inputs while saving", async () => {
+      let resolveSave: (value: unknown) => void = () => {};
+      const savePromise = new Promise((resolve) => {
+        resolveSave = resolve;
+      });
+
+      mockFetch
+        .mockResolvedValueOnce({
+          ok: true,
+          json: () => Promise.resolve(mockUser),
+        })
+        .mockReturnValueOnce({
+          ok: true,
+          json: () => savePromise,
+        });
+
+      render(<SettingsPage />);
+
+      await waitFor(() => {
+        expect(screen.getByLabelText(/cycle length/i)).toBeInTheDocument();
+      });
+
+      const cycleLengthInput = screen.getByLabelText(/cycle length/i);
+      const saveButton = screen.getByRole("button", { name: /save/i });
+      fireEvent.click(saveButton);
+
+      await waitFor(() => {
+        expect(cycleLengthInput).toBeDisabled();
+        expect(screen.getByLabelText(/notification time/i)).toBeDisabled();
+        expect(screen.getByLabelText(/timezone/i)).toBeDisabled();
+        expect(screen.getByRole("button")).toBeDisabled();
+      });
+
+      resolveSave(mockUser);
+    });
+
+    it("shows success message on save", async () => {
+      mockFetch
+        .mockResolvedValueOnce({
+          ok: true,
+          json: () => Promise.resolve(mockUser),
+        })
+        .mockResolvedValueOnce({
+          ok: true,
+          json: () => Promise.resolve({ ...mockUser, cycleLength: 30 }),
+        });
+
+      render(<SettingsPage />);
+
+      await waitFor(() => {
+        expect(screen.getByLabelText(/cycle length/i)).toBeInTheDocument();
+      });
+
+      const saveButton = screen.getByRole("button", { name: /save/i });
+      fireEvent.click(saveButton);
+
+      await waitFor(() => {
+        expect(screen.getByText(/settings saved/i)).toBeInTheDocument();
+      });
+    });
+
+    it("shows error on save failure", async () => {
+      mockFetch
+        .mockResolvedValueOnce({
+          ok: true,
+          json: () => Promise.resolve(mockUser),
+        })
+        .mockResolvedValueOnce({
+          ok: false,
+          json: () =>
+            Promise.resolve({ error: "cycleLength must be between 21 and 45" }),
+        });
+
+      render(<SettingsPage />);
+
+      await waitFor(() => {
+        expect(screen.getByLabelText(/cycle length/i)).toBeInTheDocument();
+      });
+
+      const saveButton = screen.getByRole("button", { name: /save/i });
+      fireEvent.click(saveButton);
+
+      await waitFor(() => {
+        expect(screen.getByRole("alert")).toBeInTheDocument();
+        expect(
+          screen.getByText(/cycleLength must be between 21 and 45/i),
+        ).toBeInTheDocument();
+      });
+    });
+
+    it("re-enables form after error", async () => {
+      mockFetch
+        .mockResolvedValueOnce({
+          ok: true,
+          json: () => Promise.resolve(mockUser),
+        })
+        .mockResolvedValueOnce({
+          ok: false,
+          json: () => Promise.resolve({ error: "Failed to save" }),
+        });
+
+      render(<SettingsPage />);
+
+      await waitFor(() => {
+        expect(screen.getByLabelText(/cycle length/i)).toBeInTheDocument();
+      });
+
+      const saveButton = screen.getByRole("button", { name: /save/i });
+      fireEvent.click(saveButton);
+
+      await waitFor(() => {
+        expect(screen.getByRole("alert")).toBeInTheDocument();
+      });
+
+      expect(screen.getByLabelText(/cycle length/i)).not.toBeDisabled();
+      expect(screen.getByLabelText(/notification time/i)).not.toBeDisabled();
+      expect(screen.getByLabelText(/timezone/i)).not.toBeDisabled();
+      expect(screen.getByRole("button", { name: /save/i })).not.toBeDisabled();
+    });
+  });
+
+  describe("validation", () => {
+    it("validates cycle length minimum (21)", async () => {
+      render(<SettingsPage />);
+
+      await waitFor(() => {
+        expect(screen.getByLabelText(/cycle length/i)).toBeInTheDocument();
+      });
+
+      const cycleLengthInput = screen.getByLabelText(/cycle length/i);
+      expect(cycleLengthInput).toHaveAttribute("min", "21");
+    });
+
+    it("validates cycle length maximum (45)", async () => {
+      render(<SettingsPage />);
+
+      await waitFor(() => {
+        expect(screen.getByLabelText(/cycle length/i)).toBeInTheDocument();
+      });
+
+      const cycleLengthInput = screen.getByLabelText(/cycle length/i);
+      expect(cycleLengthInput).toHaveAttribute("max", "45");
+    });
+
+    it("has cycle length input as number type", async () => {
+      render(<SettingsPage />);
+
+      await waitFor(() => {
+        expect(screen.getByLabelText(/cycle length/i)).toBeInTheDocument();
+      });
+
+      const cycleLengthInput = screen.getByLabelText(/cycle length/i);
+      expect(cycleLengthInput).toHaveAttribute("type", "number");
+    });
+
+    it("has notification time input as time type", async () => {
+      render(<SettingsPage />);
+
+      await waitFor(() => {
+        expect(screen.getByLabelText(/notification time/i)).toBeInTheDocument();
+      });
+
+      const notificationTimeInput = screen.getByLabelText(/notification time/i);
+      expect(notificationTimeInput).toHaveAttribute("type", "time");
+    });
+
+    it("requires timezone to be non-empty", async () => {
+      render(<SettingsPage />);
+
+      await waitFor(() => {
+        expect(screen.getByLabelText(/timezone/i)).toBeInTheDocument();
+      });
+
+      const timezoneInput = screen.getByLabelText(/timezone/i);
+      expect(timezoneInput).toHaveAttribute("required");
+    });
+  });
+
+  describe("error handling", () => {
+    it("clears error when user starts typing", async () => {
+      mockFetch
+        .mockResolvedValueOnce({
+          ok: true,
+          json: () => Promise.resolve(mockUser),
+        })
+        .mockResolvedValueOnce({
+          ok: false,
+          json: () => Promise.resolve({ error: "Failed to save" }),
+        });
+
+      render(<SettingsPage />);
+
+      await waitFor(() => {
+        expect(screen.getByLabelText(/cycle length/i)).toBeInTheDocument();
+      });
+
+      const saveButton = screen.getByRole("button", { name: /save/i });
+      fireEvent.click(saveButton);
+
+      await waitFor(() => {
+        expect(screen.getByRole("alert")).toBeInTheDocument();
+      });
+
+      const cycleLengthInput = screen.getByLabelText(/cycle length/i);
+      fireEvent.change(cycleLengthInput, { target: { value: "30" } });
+
+      expect(screen.queryByRole("alert")).not.toBeInTheDocument();
+    });
+
+    it("clears success message when user modifies form", async () => {
+      mockFetch
+        .mockResolvedValueOnce({
+          ok: true,
+          json: () => Promise.resolve(mockUser),
+        })
+        .mockResolvedValueOnce({
+          ok: true,
+          json: () => Promise.resolve(mockUser),
+        });
+
+      render(<SettingsPage />);
+
+      await waitFor(() => {
+        expect(screen.getByLabelText(/cycle length/i)).toBeInTheDocument();
+      });
+
+      const saveButton = screen.getByRole("button", { name: /save/i });
+      fireEvent.click(saveButton);
+
+      await waitFor(() => {
+        expect(screen.getByText(/settings saved/i)).toBeInTheDocument();
+      });
+
+      const cycleLengthInput = screen.getByLabelText(/cycle length/i);
+      fireEvent.change(cycleLengthInput, { target: { value: "30" } });
+
+      expect(screen.queryByText(/settings saved/i)).not.toBeInTheDocument();
+    });
+  });
+});
diff --git a/src/app/settings/page.tsx b/src/app/settings/page.tsx
index 262b1ea..f0fe5cd 100644
--- a/src/app/settings/page.tsx
+++ b/src/app/settings/page.tsx
@@ -1,11 +1,231 @@
 // ABOUTME: User settings page for profile and preferences.
 // ABOUTME: Allows configuration of notification time, timezone, and cycle length.
+"use client";
+
+import Link from "next/link";
+import { useCallback, useEffect, useState } from "react";
+
+interface UserData {
+  id: string;
+  email: string;
+  cycleLength: number;
+  notificationTime: string;
+  timezone: string;
+  garminConnected: boolean;
+  activeOverrides: string[];
+  lastPeriodDate: string | null;
+}
+
 export default function SettingsPage() {
+  const [userData, setUserData] = useState<UserData | null>(null);
+  const [loading, setLoading] = useState(true);
+  const [saving, setSaving] = useState(false);
+  const [error, setError] = useState<string | null>(null);
+  const [success, setSuccess] = useState<string | null>(null);
+
+  const [cycleLength, setCycleLength] = useState(28);
+  const [notificationTime, setNotificationTime] = useState("08:00");
+  const [timezone, setTimezone] = useState("");
+
+  const fetchUserData = useCallback(async () => {
+    setLoading(true);
+    setError(null);
+
+    try {
+      const response = await fetch("/api/user");
+      const data = await response.json();
+
+      if (!response.ok) {
+        throw new Error(data.error || "Failed to fetch user data");
+      }
+
+      setUserData(data);
+      setCycleLength(data.cycleLength);
+      setNotificationTime(data.notificationTime);
+      setTimezone(data.timezone);
+    } catch (err) {
+      const message = err instanceof Error ? err.message : "An error occurred";
+      setError(message);
+    } finally {
+      setLoading(false);
+    }
+  }, []);
+
+  useEffect(() => {
+    fetchUserData();
+  }, [fetchUserData]);
+
+  const handleInputChange = <T,>(
+    setter: React.Dispatch<React.SetStateAction<T>>,
+    value: T,
+  ) => {
+    setter(value);
+    if (error) {
+      setError(null);
+    }
+    if (success) {
+      setSuccess(null);
+    }
+  };
+
+  const handleSubmit = async (e: React.FormEvent<HTMLFormElement>) => {
+    e.preventDefault();
+
+    setSaving(true);
+    setError(null);
+    setSuccess(null);
+
+    try {
+      const response = await fetch("/api/user", {
+        method: "PATCH",
+        headers: { "Content-Type": "application/json" },
+        body: JSON.stringify({
+          cycleLength,
+          notificationTime,
+          timezone,
+        }),
+      });
+
+      const data = await response.json();
+
+      if (!response.ok) {
+        throw new Error(data.error || "Failed to save settings");
+      }
+
+      setUserData(data);
+      setSuccess("Settings saved successfully");
+    } catch (err) {
+      const message = err instanceof Error ? err.message : "An error occurred";
+      setError(message);
+    } finally {
+      setSaving(false);
+    }
+  };
+
+  if (loading) {
+    return (
+      <div className="container mx-auto p-8">
+        <h1 className="text-2xl font-bold mb-8">Settings</h1>
+        <p className="text-gray-500">Loading...</p>
+      </div>
+    );
+  }
+
   return (
     <div className="container mx-auto p-8">
-      <h1 className="text-2xl font-bold mb-8">Settings</h1>
-      {/* Settings form will be implemented here */}
-      <p className="text-gray-500">Settings form placeholder</p>
+      <div className="flex items-center justify-between mb-8">
+        <h1 className="text-2xl font-bold">Settings</h1>
+        <Link
+          href="/"
+          className="text-blue-600 hover:text-blue-700 hover:underline"
+        >
+          Back to Dashboard
+        </Link>
+      </div>
+
+      {error && (
+        <div
+          role="alert"
+          className="bg-red-50 border border-red-200 text-red-700 px-4 py-3 rounded mb-6"
+        >
+          {error}
+        </div>
+      )}
+
+      {success && (
+        <div className="bg-green-50 border border-green-200 text-green-700 px-4 py-3 rounded mb-6">
+          {success}
+        </div>
+      )}
+
+      <div className="max-w-lg">
+        <div className="mb-6">
+          <span className="block text-sm font-medium text-gray-700">Email</span>
+          <p className="mt-1 text-gray-900">{userData?.email}</p>
+        </div>
+
+        <form onSubmit={handleSubmit} className="space-y-6">
+          <div>
+            <label
+              htmlFor="cycleLength"
+              className="block text-sm font-medium text-gray-700"
+            >
+              Cycle Length (days)
+            </label>
+            <input
+              id="cycleLength"
+              type="number"
+              min="21"
+              max="45"
+              value={cycleLength}
+              onChange={(e) =>
+                handleInputChange(setCycleLength, Number(e.target.value))
+              }
+              disabled={saving}
+              className="mt-1 block w-full rounded-md border border-gray-300 px-3 py-2 shadow-sm focus:border-blue-500 focus:outline-none focus:ring-1 focus:ring-blue-500 disabled:bg-gray-100 disabled:cursor-not-allowed"
+              required
+            />
+            <p className="mt-1 text-sm text-gray-500">
+              Typical range: 21-45 days
+            </p>
+          </div>
+
+          <div>
+            <label
+              htmlFor="notificationTime"
+              className="block text-sm font-medium text-gray-700"
+            >
+              Notification Time
+            </label>
+            <input
+              id="notificationTime"
+              type="time"
+              value={notificationTime}
+              onChange={(e) =>
+                handleInputChange(setNotificationTime, e.target.value)
+              }
+              disabled={saving}
+              className="mt-1 block w-full rounded-md border border-gray-300 px-3 py-2 shadow-sm focus:border-blue-500 focus:outline-none focus:ring-1 focus:ring-blue-500 disabled:bg-gray-100 disabled:cursor-not-allowed"
+              required
+            />
+            <p className="mt-1 text-sm text-gray-500">
+              Time to receive daily email notification
+            </p>
+          </div>
+
+          <div>
+            <label
+              htmlFor="timezone"
+              className="block text-sm font-medium text-gray-700"
+            >
+              Timezone
+            </label>
+            <input
+              id="timezone"
+              type="text"
+              value={timezone}
+              onChange={(e) => handleInputChange(setTimezone, e.target.value)}
+              disabled={saving}
+              className="mt-1 block w-full rounded-md border border-gray-300 px-3 py-2 shadow-sm focus:border-blue-500 focus:outline-none focus:ring-1 focus:ring-blue-500 disabled:bg-gray-100 disabled:cursor-not-allowed"
+              placeholder="America/New_York"
+              required
+            />
+            <p className="mt-1 text-sm text-gray-500">
+              IANA timezone (e.g., America/New_York, Europe/London)
+            </p>
+          </div>
+
+          <div className="pt-4">
+            <button
+              type="submit"
+              disabled={saving}
+              className="w-full rounded-md bg-blue-600 px-4 py-2 text-white font-medium hover:bg-blue-700 focus:outline-none focus:ring-2 focus:ring-blue-500 focus:ring-offset-2 disabled:bg-blue-400 disabled:cursor-not-allowed"
+            >
+              {saving ? "Saving..." : "Save Settings"}
+            </button>
+          </div>
+        </form>
+      </div>
     </div>
   );
 }