diff --git a/app/f/[slug]/page.tsx b/app/f/[slug]/page.tsx
index 0f0b1f3..48ad775 100644
--- a/app/f/[slug]/page.tsx
+++ b/app/f/[slug]/page.tsx
@@ -1,9 +1,15 @@
 import type { Metadata } from "next";
 import { notFound } from "next/navigation";
 
+import { I18nProvider } from "@/components/i18n-provider";
 import { PublicFormRunner } from "@/components/public-form-runner";
 import { getPublicFormBySlug } from "@/lib/forms";
-import { getRequestI18n } from "@/lib/i18n-server";
+import { resolveAppLocale } from "@/lib/i18n";
+import {
+  getMessages,
+  getRequestI18n,
+  getRequestLocale,
+} from "@/lib/i18n-server";
 import { resolveTitle, withTitle } from "@/lib/metadata";
 
 async function getPublicForm(slug: string) {
@@ -35,10 +41,15 @@ export default async function PublicFormPage({
 }) {
   const { slug } = await params;
   const form = await getPublicForm(slug);
+  const requestLocale = await getRequestLocale();
+  const locale = resolveAppLocale(requestLocale, form.respondentLocale);
+  const messages = await getMessages(locale);
 
   return (
-    <main className="mx-auto flex w-full max-w-6xl flex-1 items-center justify-center px-6 py-8 lg:px-10 lg:py-10">
-      <PublicFormRunner form={form} />
-    </main>
+    <I18nProvider locale={locale} messages={messages}>
+      <main className="mx-auto flex w-full max-w-6xl flex-1 items-center justify-center px-6 py-8 lg:px-10 lg:py-10">
+        <PublicFormRunner form={form} />
+      </main>
+    </I18nProvider>
   );
 }
diff --git a/components/form-builder-panels.tsx b/components/form-builder-panels.tsx
index eb8f3f7..c887946 100644
--- a/components/form-builder-panels.tsx
+++ b/components/form-builder-panels.tsx
@@ -47,6 +47,13 @@ import {
   PopoverContent,
   PopoverTrigger,
 } from "@/components/ui/popover";
+import {
+  Select,
+  SelectContent,
+  SelectItem,
+  SelectTrigger,
+  SelectValue,
+} from "@/components/ui/select";
 import { Textarea } from "@/components/ui/textarea";
 import {
   blockTypeTranslationKeys,
@@ -66,6 +73,7 @@ import {
   type ChoiceOptionDraft,
 } from "@/lib/form-builder-drafts";
 import type { BuilderBlock, BuilderForm } from "@/lib/form-types";
+import { supportedLocales, type AppLocale } from "@/lib/i18n";
 
 export type FormMetadataDraft = {
   title: string;
@@ -73,6 +81,7 @@ export type FormMetadataDraft = {
   completionMessage: string;
   completionLinkLabel: string;
   completionLinkUrl: string;
+  respondentLocale: AppLocale | null;
   showProgress: boolean;
   slug: string;
 };
@@ -303,6 +312,39 @@ export function FormSettingsPanel({
           </p>
         </div>
 
+        <div className="grid gap-2 text-sm text-[var(--muted)]">
+          <span className="font-medium text-[var(--ink)]">
+            {t("builder.respondentLanguage")}
+          </span>
+          <Select
+            value={metadataDraft.respondentLocale ?? "visitor"}
+            onValueChange={(value) =>
+              setMetadataDraft((current) => ({
+                ...current,
+                respondentLocale:
+                  value === "visitor" ? null : (value as AppLocale),
+              }))
+            }
+          >
+            <SelectTrigger className="h-11 px-4 text-sm font-medium">
+              <SelectValue />
+            </SelectTrigger>
+            <SelectContent>
+              <SelectItem value="visitor">
+                {t("builder.respondentLanguageOptions.visitor")}
+              </SelectItem>
+              {supportedLocales.map((localeOption) => (
+                <SelectItem key={localeOption} value={localeOption}>
+                  {t(`settings.profile.localeOptions.${localeOption}`)}
+                </SelectItem>
+              ))}
+            </SelectContent>
+          </Select>
+          <span className="text-xs text-[var(--muted)]">
+            {t("builder.respondentLanguageHelp")}
+          </span>
+        </div>
+
         <label className="flex items-start gap-3 text-sm text-[var(--muted)]">
           <Checkbox
             checked={metadataDraft.showProgress}
diff --git a/components/form-builder.test.tsx b/components/form-builder.test.tsx
index 3a594a6..caf4917 100644
--- a/components/form-builder.test.tsx
+++ b/components/form-builder.test.tsx
@@ -4,6 +4,7 @@ import { cleanup, fireEvent, render, waitFor } from "@testing-library/react";
 import { I18nProvider } from "@/components/i18n-provider";
 import { getDefaultBlockConfig } from "@/lib/blocks";
 import type { BuilderBlock, BuilderForm } from "@/lib/form-types";
+import type { TranslationTree } from "@/lib/i18n";
 import { installTestDom } from "@/test/install-dom";
 
 const routerPushCalls: string[] = [];
@@ -52,6 +53,7 @@ function createForm(blocks: BuilderBlock[]): BuilderForm {
     completionMessage: "Thanks",
     completionLinkLabel: null,
     completionLinkUrl: null,
+    respondentLocale: null,
     showProgress: true,
     slug: "demo-form",
     status: "DRAFT",
@@ -68,9 +70,10 @@ function createForm(blocks: BuilderBlock[]): BuilderForm {
 function renderBuilder(
   initialForm: BuilderForm,
   initialMode?: "standard" | "graph",
+  messages: TranslationTree = {},
 ) {
   return render(
-    <I18nProvider locale="en" messages={{}}>
+    <I18nProvider locale="en" messages={messages}>
       <FormBuilder initialForm={initialForm} initialMode={initialMode} />
     </I18nProvider>,
   );
@@ -133,6 +136,116 @@ describe("FormBuilder", () => {
     await cleanupAndRestore(restoreDom);
   });
 
+  test("saves a restored respondent locale override from form settings", async () => {
+    const restoreDom = installTestDom();
+    const firstBlock = createBlock({
+      id: "block-1",
+      type: "SHORT_TEXT",
+      position: 0,
+      title: "First question",
+    });
+    const fetchCalls: Array<{ url: string; init?: RequestInit }> = [];
+    const previousFetch = globalThis.fetch;
+
+    globalThis.fetch = (async (
+      url: string | URL | Request,
+      init?: RequestInit,
+    ) => {
+      fetchCalls.push({ url: String(url), init });
+
+      return {
+        ok: true,
+        json: async () => ({
+          form: {
+            ...createForm([firstBlock]),
+            respondentLocale: "ru",
+          },
+        }),
+      } as Response;
+    }) as typeof fetch;
+
+    const view = renderBuilder(
+      {
+        ...createForm([firstBlock]),
+        respondentLocale: "ru",
+      },
+      undefined,
+      {
+        builder: { saveFormSettings: "Save form settings" },
+      },
+    );
+
+    fireEvent.click(view.getByRole("button", { name: "builder.settings" }));
+
+    await waitFor(() => {
+      expect(view.getByText("builder.settingsTitle") !== null).toBe(true);
+    });
+
+    fireEvent.click(view.getByRole("button", { name: "Save form settings" }));
+
+    await waitFor(() => {
+      expect(fetchCalls.length).toBe(1);
+    });
+
+    expect(fetchCalls[0]?.url).toBe("/api/forms/form-1");
+    expect(fetchCalls[0]?.init?.method).toBe("PATCH");
+    expect(String(fetchCalls[0]?.init?.body)).toContain(
+      '"respondentLocale":"ru"',
+    );
+
+    globalThis.fetch = previousFetch;
+    await cleanupAndRestore(restoreDom);
+  });
+
+  test("saves visitor-language mode from form settings", async () => {
+    const restoreDom = installTestDom();
+    const firstBlock = createBlock({
+      id: "block-1",
+      type: "SHORT_TEXT",
+      position: 0,
+      title: "First question",
+    });
+    const fetchCalls: Array<{ url: string; init?: RequestInit }> = [];
+    const previousFetch = globalThis.fetch;
+
+    globalThis.fetch = (async (
+      url: string | URL | Request,
+      init?: RequestInit,
+    ) => {
+      fetchCalls.push({ url: String(url), init });
+
+      return {
+        ok: true,
+        json: async () => ({
+          form: createForm([firstBlock]),
+        }),
+      } as Response;
+    }) as typeof fetch;
+
+    const view = renderBuilder(createForm([firstBlock]), undefined, {
+      builder: { saveFormSettings: "Save form settings" },
+    });
+
+    fireEvent.click(view.getByRole("button", { name: "builder.settings" }));
+
+    await waitFor(() => {
+      expect(view.getByText("builder.settingsTitle") !== null).toBe(true);
+    });
+
+    fireEvent.click(view.getByRole("button", { name: "Save form settings" }));
+
+    await waitFor(() => {
+      expect(fetchCalls.length).toBe(1);
+    });
+
+    expect(String(fetchCalls[0]?.init?.body)).toContain(
+      '"respondentLocale":null',
+    );
+
+    globalThis.fetch = previousFetch;
+    await cleanupAndRestore(restoreDom);
+  });
+
   test("lets the creator cancel or discard unsaved changes before opening form settings", async () => {
     const restoreDom = installTestDom();
     const firstBlock = createBlock({
diff --git a/components/form-builder.tsx b/components/form-builder.tsx
index c1cbee7..98056a0 100644
--- a/components/form-builder.tsx
+++ b/components/form-builder.tsx
@@ -284,6 +284,7 @@ export function FormBuilder({
     completionMessage: initialForm.completionMessage,
     completionLinkLabel: initialForm.completionLinkLabel ?? "",
     completionLinkUrl: initialForm.completionLinkUrl ?? "",
+    respondentLocale: initialForm.respondentLocale,
     showProgress: initialForm.showProgress,
     slug: initialForm.slug,
   });
@@ -374,6 +375,7 @@ export function FormBuilder({
       completionMessage: form.completionMessage,
       completionLinkLabel: form.completionLinkLabel ?? "",
       completionLinkUrl: form.completionLinkUrl ?? "",
+      respondentLocale: form.respondentLocale,
       showProgress: form.showProgress,
       slug: form.slug,
     });
@@ -383,6 +385,7 @@ export function FormBuilder({
     form.completionMessage,
     form.completionLinkLabel,
     form.completionLinkUrl,
+    form.respondentLocale,
     form.showProgress,
     form.slug,
   ]);
diff --git a/lib/form-metadata-schema.test.ts b/lib/form-metadata-schema.test.ts
new file mode 100644
index 0000000..30e0e8d
--- /dev/null
+++ b/lib/form-metadata-schema.test.ts
@@ -0,0 +1,24 @@
+import { describe, expect, test } from "bun:test";
+
+import { formMetadataSchema } from "@/lib/validators";
+
+describe("formMetadataSchema", () => {
+  test("keeps a supported respondent locale override", () => {
+    const parsed = formMetadataSchema.parse({
+      title: "Demo form",
+      slug: "demo-form",
+      respondentLocale: "ru",
+    });
+
+    expect(parsed.respondentLocale).toBe("ru");
+  });
+
+  test("defaults respondent locale to visitor language mode", () => {
+    const parsed = formMetadataSchema.parse({
+      title: "Demo form",
+      slug: "demo-form",
+    });
+
+    expect(parsed.respondentLocale).toBe(null);
+  });
+});
diff --git a/lib/form-types.ts b/lib/form-types.ts
index 7b5023a..5c6e595 100644
--- a/lib/form-types.ts
+++ b/lib/form-types.ts
@@ -1,6 +1,7 @@
 import type { FormStatus, OrganizationMemberRole } from "@prisma/client";
 
 import type { SerializedBlock } from "@/lib/blocks";
+import type { AppLocale } from "@/lib/i18n";
 
 export type BuilderBlock = SerializedBlock;
 export type PublicBlock = SerializedBlock;
@@ -44,6 +45,7 @@ export type BuilderForm = {
   completionMessage: string;
   completionLinkLabel: string | null;
   completionLinkUrl: string | null;
+  respondentLocale: AppLocale | null;
   showProgress: boolean;
   slug: string;
   status: FormStatus;
@@ -61,6 +63,7 @@ export type PublicForm = {
   completionMessage: string;
   completionLinkLabel: string | null;
   completionLinkUrl: string | null;
+  respondentLocale: AppLocale | null;
   showProgress: boolean;
   slug: string;
   blocks: PublicBlock[];
diff --git a/lib/forms.ts b/lib/forms.ts
index 8108cbd..5408b0d 100644
--- a/lib/forms.ts
+++ b/lib/forms.ts
@@ -39,7 +39,12 @@ import {
   reorderBlocksSchema,
 } from "@/lib/validators";
 import { slugify } from "@/lib/utils";
-import { DEFAULT_LOCALE, translate, type AppLocale } from "@/lib/i18n";
+import {
+  DEFAULT_LOCALE,
+  normalizeLocale,
+  translate,
+  type AppLocale,
+} from "@/lib/i18n";
 import { getMessages } from "@/lib/i18n-server";
 import { normalizeBlockConfig } from "@/lib/block-config-normalization";
 import {
@@ -122,6 +127,9 @@ function toBuilderForm(form: BuilderFormRecord): BuilderForm {
     completionMessage: form.completionMessage,
     completionLinkLabel: form.completionLinkLabel,
     completionLinkUrl: form.completionLinkUrl,
+    respondentLocale: form.respondentLocale
+      ? normalizeLocale(form.respondentLocale)
+      : null,
     showProgress: form.showProgress,
     slug: form.slug,
     status: form.status,
@@ -141,6 +149,9 @@ function toPublicForm(form: Form & { blocks: FormBlock[] }): PublicForm {
     completionMessage: form.completionMessage,
     completionLinkLabel: form.completionLinkLabel,
     completionLinkUrl: form.completionLinkUrl,
+    respondentLocale: form.respondentLocale
+      ? normalizeLocale(form.respondentLocale)
+      : null,
     showProgress: form.showProgress,
     slug: form.slug,
     blocks: form.blocks.map(serializeBlock),
diff --git a/lib/i18n.test.ts b/lib/i18n.test.ts
new file mode 100644
index 0000000..c0effd7
--- /dev/null
+++ b/lib/i18n.test.ts
@@ -0,0 +1,17 @@
+import { describe, expect, test } from "bun:test";
+
+import { resolveAppLocale } from "@/lib/i18n";
+
+describe("resolveAppLocale", () => {
+  test("uses the explicit override before request locale", () => {
+    expect(resolveAppLocale("en", "ru")).toBe("ru");
+  });
+
+  test("falls back to the preferred locale when no override is set", () => {
+    expect(resolveAppLocale("ru", null)).toBe("ru");
+  });
+
+  test("falls back to English for unsupported override values", () => {
+    expect(resolveAppLocale("ru", "de")).toBe("en");
+  });
+});
diff --git a/lib/i18n.ts b/lib/i18n.ts
index e52eba3..f9ad379 100644
--- a/lib/i18n.ts
+++ b/lib/i18n.ts
@@ -20,6 +20,17 @@ export function normalizeLocale(value: string | null | undefined): AppLocale {
   return isSupportedLocale(base) ? base : DEFAULT_LOCALE;
 }
 
+export function resolveAppLocale(
+  preferredLocale: string | null | undefined,
+  overrideLocale?: string | null,
+): AppLocale {
+  if (typeof overrideLocale !== "undefined" && overrideLocale !== null) {
+    return normalizeLocale(overrideLocale);
+  }
+
+  return normalizeLocale(preferredLocale);
+}
+
 export function resolveBrowserLocale(
   headerValue: string | null | undefined,
 ): AppLocale {
diff --git a/lib/public-form-draft.test.ts b/lib/public-form-draft.test.ts
index 5f88a8a..681e3ac 100644
--- a/lib/public-form-draft.test.ts
+++ b/lib/public-form-draft.test.ts
@@ -17,6 +17,7 @@ function createForm(blocks: SerializedBlock[]): PublicForm {
     completionMessage: "Done",
     completionLinkLabel: null,
     completionLinkUrl: null,
+    respondentLocale: null,
     showProgress: true,
     slug: "demo-form",
     blocks,
diff --git a/lib/validators.ts b/lib/validators.ts
index 8e3592b..b9123da 100644
--- a/lib/validators.ts
+++ b/lib/validators.ts
@@ -11,6 +11,7 @@ export const formMetadataSchema = z
     completionMessage: z.string().trim().max(600).default(""),
     completionLinkLabel: z.string().trim().max(80).default(""),
     completionLinkUrl: z.string().trim().max(2048).default(""),
+    respondentLocale: z.enum(supportedLocales).nullable().default(null),
     showProgress: z.boolean().default(true),
     slug: z
       .string()
@@ -59,6 +60,7 @@ export const formMetadataSchema = z
   })
   .transform((value) => ({
     ...value,
+    respondentLocale: value.respondentLocale ?? null,
     completionLinkLabel: value.completionLinkLabel || null,
     completionLinkUrl: value.completionLinkUrl || null,
   }));
diff --git a/locales/en.yml b/locales/en.yml
index 2889994..7839434 100644
--- a/locales/en.yml
+++ b/locales/en.yml
@@ -161,6 +161,10 @@ builder:
   publicRouteHelp: Published forms accept anonymous submissions. Changes to a published form go live immediately.
   appearance: Appearance
   appearanceDescription: Control what respondents see while moving through the form.
+  respondentLanguage: Respondent interface language
+  respondentLanguageHelp: Choose the language used for buttons, validation, progress, and other interface text in the public form.
+  respondentLanguageOptions:
+    visitor: Use visitor's language
   showProgress: Show form progress
   copyLink: Copy link
   openRunner: Open runner
diff --git a/locales/ru.yml b/locales/ru.yml
index 5d68638..de0b42a 100644
--- a/locales/ru.yml
+++ b/locales/ru.yml
@@ -161,6 +161,10 @@ builder:
   publicRouteHelp: Опубликованные формы принимают анонимные ответы. Изменения в опубликованной форме становятся доступны сразу.
   appearance: Внешний вид
   appearanceDescription: Управляйте тем, что респонденты видят во время прохождения формы.
+  respondentLanguage: Язык интерфейса для респондента
+  respondentLanguageHelp: Выберите язык кнопок, валидации, прогресса и другого интерфейсного текста в публичной форме.
+  respondentLanguageOptions:
+    visitor: Использовать язык посетителя
   showProgress: Показывать прогресс формы
   copyLink: Скопировать ссылку
   openRunner: Открыть раннер
diff --git a/openspec/changes/archive/2026-04-15-add-form-locale-override/.openspec.yaml b/openspec/changes/archive/2026-04-15-add-form-locale-override/.openspec.yaml
new file mode 100644
index 0000000..859e7bb
--- /dev/null
+++ b/openspec/changes/archive/2026-04-15-add-form-locale-override/.openspec.yaml
@@ -0,0 +1,2 @@
+schema: spec-driven
+created: 2026-04-15
diff --git a/openspec/changes/archive/2026-04-15-add-form-locale-override/design.md b/openspec/changes/archive/2026-04-15-add-form-locale-override/design.md
new file mode 100644
index 0000000..4bb52b2
--- /dev/null
+++ b/openspec/changes/archive/2026-04-15-add-form-locale-override/design.md
@@ -0,0 +1,70 @@
+## Context
+
+Public form routes currently render localized interface strings from the active request locale, which is derived from supported browser or user-preference signals and then normalized to a supported language. That keeps general localization simple, but it does not give creators a way to keep a specific form's respondent-facing interface aligned with the language of the form content itself. This change crosses creator settings, stored form metadata, public-form loading, and locale resolution, so a short design is useful before implementation.
+
+## Goals / Non-Goals
+
+**Goals:**
+- Let a creator choose a respondent interface locale override per form.
+- Preserve existing visitor-language detection when no override is configured.
+- Keep locale handling limited to the existing supported locales and fallback-to-English behavior.
+- Make the public runner, validation copy, progress labels, and completion state honor the saved override consistently.
+
+**Non-Goals:**
+- Auto-translating form content authored by creators.
+- Adding new supported languages in this change.
+- Introducing per-block or per-section locale settings.
+- Changing creator-dashboard locale behavior outside the form settings needed to edit the override.
+
+## Decisions
+
+### 1. Store locale override as form metadata, not as a transient request preference
+The system will persist a nullable form-level locale override alongside other form settings. `null` means the `Use visitor's language` mode; a supported locale value such as `en` or `ru` means the public runner must use that locale for respondent-facing UI.
+
+**Why:** The override is part of the form's authored behavior, similar to title, completion content, and slug. It must survive draft saves, publication, and later edits.
+
+**Alternatives considered:**
+- Store override only in published snapshots: rejected because creators need to preview and edit draft behavior.
+- Store override in browser local state: rejected because the setting belongs to the form, not the current creator session.
+
+### 2. Apply the override only on public respondent-facing form surfaces
+The override will affect public form routes and the locale used to prepare public runner strings. Creator-facing builder chrome will continue to follow the creator/session locale.
+
+**Why:** The problem is respondent experience mismatch, not creator workspace localization. Keeping creator surfaces on their own locale avoids surprising workspace-wide language switches while editing a form.
+
+**Alternatives considered:**
+- Also force the builder locale while editing that form: rejected because it would couple one form's language to the whole creator session and make mixed-language workspaces harder to use.
+
+### 3. Resolve locale with clear precedence: form override first, then existing detection, then fallback
+For public forms, locale resolution will first check the saved form override. If absent, the system will continue using the current supported-locale detection flow. Unsupported or malformed values will still normalize to English.
+
+**Why:** This preserves the existing localization model while adding one explicit author-controlled override point.
+
+**Alternatives considered:**
+- Let browser locale override the form setting: rejected because it does not solve the reported inconsistency.
+- Remove browser locale detection entirely: rejected because visitor-language localization remains desirable for forms without an override.
+
+### 4. Keep the saved value constrained to supported locales
+The builder setting and persistence layer will only allow `null`, `en`, or `ru` initially.
+
+**Why:** The app already validates locale support centrally. Reusing that contract keeps runtime behavior predictable and avoids publishing forms with unusable locale values.
+
+**Alternatives considered:**
+- Allow arbitrary BCP-47 locale codes for future-proofing: rejected because the application only ships `en` and `ru` resources today.
+
+## Risks / Trade-offs
+
+- [Creators may expect form content itself to be translated] → Mitigation: label the setting as interface language for respondent UI, not content translation.
+- [Existing public-form locale loading may have multiple entry points] → Mitigation: centralize override-aware resolution in the shared public-form loading/i18n path instead of duplicating precedence logic.
+- [Stored invalid values from manual edits or future bugs could break rendering] → Mitigation: normalize persisted locale override through the existing supported-locale fallback helper.
+- [Previewing draft behavior may differ from published behavior if override is not included in all serialization paths] → Mitigation: update both creator draft payloads and public form payload generation to carry the same field.
+
+## Migration Plan
+
+- Add a nullable persisted locale override field or config value with default `null` for existing forms.
+- Treat missing values on existing records as `Use visitor's language`.
+- Rollback is low risk: code can ignore the field and continue using current locale detection, with existing saved `null`/supported values remaining harmless.
+
+## Open Questions
+
+- None currently. The product intent is clear enough to proceed with a form-level override using existing supported locales.
diff --git a/openspec/changes/archive/2026-04-15-add-form-locale-override/proposal.md b/openspec/changes/archive/2026-04-15-add-form-locale-override/proposal.md
new file mode 100644
index 0000000..2f69aad
--- /dev/null
+++ b/openspec/changes/archive/2026-04-15-add-form-locale-override/proposal.md
@@ -0,0 +1,27 @@
+## Why
+
+Public form runners currently localize respondent-facing interface strings from browser or system locale. That can produce a mixed-language experience when a creator builds a form in one language but the respondent's device prefers another, especially for labels such as navigation, validation, progress, and completion UI. Adding a per-form locale override makes respondent-facing copy consistent with the language the creator intends for that form.
+
+## What Changes
+
+- Add a form-level setting that lets creators choose whether a form's respondent-facing interface uses `Use visitor's language` or forces a specific supported locale.
+- Persist the selected locale override as part of form metadata so draft and published forms keep the same respondent-language behavior.
+- Apply the form-level locale override on public form routes so runner UI, validation messages, progress text, and completion-state interface strings render in the configured locale.
+- Keep supported-locale fallback behavior intact so invalid or unsupported saved values resolve safely to English.
+
+## Capabilities
+
+### New Capabilities
+- None.
+
+### Modified Capabilities
+- `conversational-form-builder`: creators can configure a per-form respondent interface locale override in form settings.
+- `anonymous-form-runner`: public form routes resolve respondent-facing UI locale from the form override before using browser locale detection.
+- `site-localization`: locale resolution supports a saved form-specific override for public form surfaces while preserving supported-locale fallback rules.
+
+## Impact
+
+- Affected code: creator form settings UI, form serialization and persistence, public form route loading, i18n locale resolution, and respondent runner rendering.
+- APIs: form metadata payloads and public form data loading will include the saved locale override.
+- Data model: forms need a persisted locale override field or equivalent config value.
+- Dependencies: no new external dependencies expected.
diff --git a/openspec/changes/archive/2026-04-15-add-form-locale-override/specs/anonymous-form-runner/spec.md b/openspec/changes/archive/2026-04-15-add-form-locale-override/specs/anonymous-form-runner/spec.md
new file mode 100644
index 0000000..000cc9e
--- /dev/null
+++ b/openspec/changes/archive/2026-04-15-add-form-locale-override/specs/anonymous-form-runner/spec.md
@@ -0,0 +1,12 @@
+## ADDED Requirements
+
+### Requirement: Public form runner honors form-specific interface locale overrides
+The system SHALL resolve respondent-facing interface strings for a public form from the form's saved locale override when one is configured. When no override is configured, the system SHALL continue using the existing automatic locale-detection flow.
+
+#### Scenario: Respondent opens a form with a Russian locale override
+- **WHEN** a respondent opens a published form whose saved respondent interface locale override is `ru`
+- **THEN** the public runner renders navigation, validation, progress, and completion interface strings in Russian regardless of the respondent's browser locale
+
+#### Scenario: Respondent opens a form with no locale override
+- **WHEN** a respondent opens a published form that has no saved respondent interface locale override
+- **THEN** the public runner resolves interface strings using the existing automatic locale-detection behavior
diff --git a/openspec/changes/archive/2026-04-15-add-form-locale-override/specs/conversational-form-builder/spec.md b/openspec/changes/archive/2026-04-15-add-form-locale-override/specs/conversational-form-builder/spec.md
new file mode 100644
index 0000000..3161311
--- /dev/null
+++ b/openspec/changes/archive/2026-04-15-add-form-locale-override/specs/conversational-form-builder/spec.md
@@ -0,0 +1,16 @@
+## ADDED Requirements
+
+### Requirement: Creator can configure respondent interface locale per form
+The system SHALL allow an authenticated creator to configure a form-level respondent interface locale in form settings for any accessible form. The setting SHALL support a `Use visitor's language` option and any currently supported explicit locale override.
+
+#### Scenario: Creator uses visitor-language mode
+- **WHEN** an authenticated creator leaves the respondent interface locale setting on `Use visitor's language`
+- **THEN** the system saves the form without an explicit locale override
+
+#### Scenario: Creator selects a supported explicit locale
+- **WHEN** an authenticated creator chooses a supported locale such as English or Russian in form settings and saves
+- **THEN** the system persists that locale as the form's respondent interface override
+
+#### Scenario: Creator reopens form settings with an existing locale override
+- **WHEN** an authenticated creator opens settings for a form that already has a saved respondent interface locale override
+- **THEN** the system shows the saved override as the current selected value
diff --git a/openspec/changes/archive/2026-04-15-add-form-locale-override/specs/site-localization/spec.md b/openspec/changes/archive/2026-04-15-add-form-locale-override/specs/site-localization/spec.md
new file mode 100644
index 0000000..a4e13eb
--- /dev/null
+++ b/openspec/changes/archive/2026-04-15-add-form-locale-override/specs/site-localization/spec.md
@@ -0,0 +1,20 @@
+## MODIFIED Requirements
+
+### Requirement: Supported locale resolution falls back to English
+The system SHALL support `en` and `ru` locales initially and SHALL normalize unsupported locale values to English. For public form surfaces, the system SHALL honor a saved supported form-level locale override before using browser or user-state locale detection.
+
+#### Scenario: Supported locale is requested
+- **WHEN** the active locale is `en` or `ru`
+- **THEN** the system renders strings from that supported locale resource set
+
+#### Scenario: Public form has a supported locale override
+- **WHEN** a public form surface is loaded for a form whose saved locale override is `en` or `ru`
+- **THEN** the system uses that saved form locale for rendering instead of browser locale detection
+
+#### Scenario: Unauthenticated user has a supported browser locale
+- **WHEN** an unauthenticated creator or respondent opens the app and no form-level locale override applies while the browser locale resolves to a supported locale
+- **THEN** the system uses that supported browser locale for rendering without requiring sign-in
+
+#### Scenario: Unsupported locale is requested
+- **WHEN** the system receives an unsupported locale value from user state, OAuth data, environment detection, or a saved form override
+- **THEN** the system falls back to English as the active locale
diff --git a/openspec/changes/archive/2026-04-15-add-form-locale-override/tasks.md b/openspec/changes/archive/2026-04-15-add-form-locale-override/tasks.md
new file mode 100644
index 0000000..18ec536
--- /dev/null
+++ b/openspec/changes/archive/2026-04-15-add-form-locale-override/tasks.md
@@ -0,0 +1,17 @@
+## 1. Form metadata and persistence
+
+- [x] 1.1 Add a nullable respondent interface locale override field to form metadata/domain types with supported-locale validation and `Use visitor's language` as the no-override/default mode.
+- [x] 1.2 Include the locale override in form settings load/save flows and any form serialization used by the builder.
+- [x] 1.3 Add or update tests covering persisted form locale override normalization and round-tripping.
+
+## 2. Creator settings UI
+
+- [x] 2.1 Add a form settings control that lets creators choose `Use visitor's language` or a supported explicit respondent interface locale.
+- [x] 2.2 Ensure the builder restores the saved selection when reopening form settings and persists changes through the existing save action.
+- [x] 2.3 Add UI tests covering selecting, saving, and reloading the form locale override.
+
+## 3. Public locale resolution
+
+- [x] 3.1 Update public form loading/i18n resolution so a saved form locale override takes precedence over automatic locale detection on respondent-facing routes.
+- [x] 3.2 Ensure public runner strings, validation copy, progress text, and completion UI all read from the resolved override-aware locale.
+- [x] 3.3 Add tests covering explicit override precedence, `Use visitor's language` fallback behavior, and unsupported-value fallback to English.
diff --git a/openspec/specs/anonymous-form-runner/spec.md b/openspec/specs/anonymous-form-runner/spec.md
index b28db31..46ff2f0 100644
--- a/openspec/specs/anonymous-form-runner/spec.md
+++ b/openspec/specs/anonymous-form-runner/spec.md
@@ -142,3 +142,14 @@ The system SHALL render the supported authored Markdown subset in the public run
 #### Scenario: Respondent views a formatted question description
 - **WHEN** a published form contains a question description with supported Markdown
 - **THEN** the runner shows the formatted description consistently with the shared authored Markdown rules
+
+### Requirement: Public form runner honors form-specific interface locale overrides
+The system SHALL resolve respondent-facing interface strings for a public form from the form's saved locale override when one is configured. When no override is configured, the system SHALL continue using the existing automatic locale-detection flow.
+
+#### Scenario: Respondent opens a form with a Russian locale override
+- **WHEN** a respondent opens a published form whose saved respondent interface locale override is `ru`
+- **THEN** the public runner renders navigation, validation, progress, and completion interface strings in Russian regardless of the respondent's browser locale
+
+#### Scenario: Respondent opens a form with no locale override
+- **WHEN** a respondent opens a published form that has no saved respondent interface locale override
+- **THEN** the public runner resolves interface strings using the existing automatic locale-detection behavior
diff --git a/openspec/specs/conversational-form-builder/spec.md b/openspec/specs/conversational-form-builder/spec.md
index f79ba5a..12ad35c 100644
--- a/openspec/specs/conversational-form-builder/spec.md
+++ b/openspec/specs/conversational-form-builder/spec.md
@@ -129,6 +129,21 @@ The system SHALL allow an authenticated creator to edit the completion content f
 - **WHEN** an authenticated creator leaves the follow-up link label or URL empty
 - **THEN** the system does not save or expose a partial follow-up link for the form
 
+### Requirement: Creator can configure respondent interface locale per form
+The system SHALL allow an authenticated creator to configure a form-level respondent interface locale in form settings for any accessible form. The setting SHALL support a `Use visitor's language` option and any currently supported explicit locale override.
+
+#### Scenario: Creator uses visitor-language mode
+- **WHEN** an authenticated creator leaves the respondent interface locale setting on `Use visitor's language`
+- **THEN** the system saves the form without an explicit locale override
+
+#### Scenario: Creator selects a supported explicit locale
+- **WHEN** an authenticated creator chooses a supported locale such as English or Russian in form settings and saves
+- **THEN** the system persists that locale as the form's respondent interface override
+
+#### Scenario: Creator reopens form settings with an existing locale override
+- **WHEN** an authenticated creator opens settings for a form that already has a saved respondent interface locale override
+- **THEN** the system shows the saved override as the current selected value
+
 ### Requirement: Builder reflects the active workspace context
 The system SHALL show the active workspace context when a creator creates or edits a form so they can tell whether the form belongs to their personal workspace or an organization.
 
diff --git a/openspec/specs/site-localization/spec.md b/openspec/specs/site-localization/spec.md
index 965956a..306eb35 100644
--- a/openspec/specs/site-localization/spec.md
+++ b/openspec/specs/site-localization/spec.md
@@ -12,18 +12,22 @@ The system SHALL resolve user-facing application strings from locale-specific YA
 - **THEN** the system can render that surface in the additional language without requiring the component to hardcode translated copy
 
 ### Requirement: Supported locale resolution falls back to English
-The system SHALL support `en` and `ru` locales initially and SHALL normalize unsupported locale values to English.
+The system SHALL support `en` and `ru` locales initially and SHALL normalize unsupported locale values to English. For public form surfaces, the system SHALL honor a saved supported form-level locale override before using browser or user-state locale detection.
 
 #### Scenario: Supported locale is requested
 - **WHEN** the active locale is `en` or `ru`
 - **THEN** the system renders strings from that supported locale resource set
 
+#### Scenario: Public form has a supported locale override
+- **WHEN** a public form surface is loaded for a form whose saved locale override is `en` or `ru`
+- **THEN** the system uses that saved form locale for rendering instead of browser locale detection
+
 #### Scenario: Unauthenticated user has a supported browser locale
-- **WHEN** an unauthenticated creator or respondent opens the app and the browser locale resolves to a supported locale
+- **WHEN** an unauthenticated creator or respondent opens the app and no form-level locale override applies while the browser locale resolves to a supported locale
 - **THEN** the system uses that supported browser locale for rendering without requiring sign-in
 
 #### Scenario: Unsupported locale is requested
-- **WHEN** the system receives an unsupported locale value from user state, OAuth data, or environment detection
+- **WHEN** the system receives an unsupported locale value from user state, OAuth data, environment detection, or a saved form override
 - **THEN** the system falls back to English as the active locale
 
 ### Requirement: Missing translations are surfaced during build
diff --git a/prisma/migrations/20260415132310_add_form_respondent_locale/migration.sql b/prisma/migrations/20260415132310_add_form_respondent_locale/migration.sql
new file mode 100644
index 0000000..af56aa4
--- /dev/null
+++ b/prisma/migrations/20260415132310_add_form_respondent_locale/migration.sql
@@ -0,0 +1,2 @@
+-- AlterTable
+ALTER TABLE "Form" ADD COLUMN     "respondentLocale" TEXT;
diff --git a/prisma/schema.prisma b/prisma/schema.prisma
index 1ae19fe..53ed583 100644
--- a/prisma/schema.prisma
+++ b/prisma/schema.prisma
@@ -95,6 +95,7 @@ model Form {
   completionMessage   String        @default("")
   completionLinkLabel String?
   completionLinkUrl   String?
+  respondentLocale    String?
   showProgress        Boolean       @default(true)
   slug                String        @unique
   status              FormStatus    @default(DRAFT)