diff --git a/.circleci/config.yml b/.circleci/config.yml
index 6c857e45b..25b3dc430 100644
--- a/.circleci/config.yml
+++ b/.circleci/config.yml
@@ -9,6 +9,7 @@ jobs:
           DEBUG: yup
           ENABLE_WEBPACK_CONTENT_HASH: yup
           ENABLE_FINDHELP: yup
+          ENABLE_I18N: yup
           SPATIALITE_LIBRARY_PATH: mod_spatialite
           CC_TEST_REPORTER_ID: 0b47f78787493d017e97f3f141ab138e9188d1ebbe149bb0f28a8ff3314dfdd7
     steps:
diff --git a/airtable/tests/test_record.py b/airtable/tests/test_record.py
index 78ca94e5e..d26425255 100644
--- a/airtable/tests/test_record.py
+++ b/airtable/tests/test_record.py
@@ -3,6 +3,7 @@
 
 from users.tests.factories import UserFactory
 from onboarding.tests.factories import OnboardingInfoFactory
+from project.tests.util import strip_locale
 from loc.tests.factories import LetterRequestFactory, LandlordDetailsFactory
 from airtable.record import Fields
 
@@ -48,7 +49,7 @@ def test_from_user_works_with_letter_request():
     fields = Fields.from_user(lr.user)
     assert fields.letter_request__will_we_mail is True
     assert fields.letter_request__created_at == datetime.datetime.utcnow().date().isoformat()
-    assert fields.letter_request__admin_pdf_url == \
+    assert strip_locale(fields.letter_request__admin_pdf_url) == \
         f'https://example.com/loc/admin/{lr.user.pk}/letter.pdf'
 
 
diff --git a/frontend/lambda/lambda.tsx b/frontend/lambda/lambda.tsx
index 60bae390d..cd048f0d5 100644
--- a/frontend/lambda/lambda.tsx
+++ b/frontend/lambda/lambda.tsx
@@ -24,6 +24,7 @@ import Helmet from 'react-helmet';
 import { ErrorDisplay, getErrorString } from '../lib/error-boundary';
 import { App, AppProps } from '../lib/app';
 import { appStaticContextAsStaticRouterContext, AppStaticContext } from '../lib/app-static-context';
+import i18n from '../lib/i18n';
 
 const readFile = promisify(fs.readFile);
 
@@ -110,6 +111,7 @@ export function getBundleFiles(files: { file: string }[]): string[] {
  *   lazy loading purposes.
  */
 function generateResponse(event: AppProps, bundleStats: any): Promise<LambdaResponse> {
+  i18n.initialize(event.locale);
   return new Promise<LambdaResponse>(resolve => {
     const context: AppStaticContext = {
       statusCode: 200,
diff --git a/frontend/lambda/tests/lambda.test.tsx b/frontend/lambda/tests/lambda.test.tsx
index 4432abb36..17e89d79d 100644
--- a/frontend/lambda/tests/lambda.test.tsx
+++ b/frontend/lambda/tests/lambda.test.tsx
@@ -8,6 +8,7 @@ import { FakeServerInfo, FakeSessionInfo } from '../../lib/tests/util';
 
 const fakeAppProps: AppProps = {
   initialURL: '/',
+  locale: '',
   server: FakeServerInfo,
   initialSession: FakeSessionInfo
 };
diff --git a/frontend/lib/app.tsx b/frontend/lib/app.tsx
index 130c026e4..42d084e81 100644
--- a/frontend/lib/app.tsx
+++ b/frontend/lib/app.tsx
@@ -28,6 +28,13 @@ export interface AppProps {
   /** The initial URL to render on page load. */
   initialURL: string;
 
+  /**
+   * The locale the user is on. This can be an empty string to
+   * indicate that localization is disabled, or an ISO 639-1
+   * code such as 'en' or 'es'.
+   */
+  locale: string;
+
   /** The initial session state the App was started with. */
   initialSession: AllSessionInfo;
 
@@ -189,22 +196,30 @@ export class AppWithoutRouter extends React.Component<AppPropsWithRouter, AppSta
   renderRoutes(location: Location<any>): JSX.Element {
     return (
       <Switch location={location}>
-        <Route path={Routes.home} exact>
+        <Route path={Routes.locale.home} exact>
           <LoadableIndexPage isLoggedIn={this.isLoggedIn} />
         </Route>
-        <Route path={Routes.login} exact component={LoginPage} />
+        <Route path={Routes.locale.login} exact component={LoginPage} />
         <Route path={Routes.adminLogin} exact component={LoginPage} />
-        <Route path={Routes.logout} exact component={LogoutPage} />
+        <Route path={Routes.locale.logout} exact component={LogoutPage} />
         {getOnboardingRouteForIntent(OnboardingInfoSignupIntent.LOC)}
-        <Route path={Routes.loc.prefix} component={LoadableLetterOfComplaintRoutes} />
+        <Route path={Routes.locale.loc.prefix} component={LoadableLetterOfComplaintRoutes} />
         {getOnboardingRouteForIntent(OnboardingInfoSignupIntent.HP)}
-        <Route path={Routes.hp.prefix} component={LoadableHPActionRoutes} />
+        <Route path={Routes.locale.hp.prefix} component={LoadableHPActionRoutes} />
         <Route path={Routes.dev.prefix} component={LoadableDevRoutes} />
         <Route render={NotFound} />
       </Switch>
     );
   }
 
+  renderRoute(props: RouteComponentProps<any>): JSX.Element {
+    const { pathname } = props.location;
+    if (routeMap.exists(pathname)) {
+      return this.renderRoutes(props.location);
+    }
+    return NotFound(props);
+  }
+
   render() {
     if (this.props.modal) {
       return <AppContext.Provider value={this.getAppContext()} children={this.props.modal} />
@@ -220,12 +235,7 @@ export class AppWithoutRouter extends React.Component<AppPropsWithRouter, AppSta
                   <div className="container" ref={this.pageBodyRef}
                       data-jf-is-noninteractive tabIndex={-1}>
                     <LoadingOverlayManager>
-                      <Route render={(props) => {
-                        if (routeMap.exists(props.location.pathname)) {
-                          return this.renderRoutes(props.location);
-                        }
-                        return NotFound(props);
-                      }}/>
+                      <Route render={(props) => this.renderRoute(props)}/>
                     </LoadingOverlayManager>
                   </div>
                 </section>
diff --git a/frontend/lib/dev.tsx b/frontend/lib/dev.tsx
index 57beda3f5..2b41a736e 100644
--- a/frontend/lib/dev.tsx
+++ b/frontend/lib/dev.tsx
@@ -75,7 +75,7 @@ export default function DevRoutes(): JSX.Element {
   return (
     <Switch>
        <Route path={Routes.dev.home} exact component={DevHome} />
-       <Route path={Routes.dev.examples.redirect} exact render={() => <Redirect to="/" />} />
+       <Route path={Routes.dev.examples.redirect} exact render={() => <Redirect to={Routes.locale.home} />} />
        <Route path={Routes.dev.examples.modal} exact component={LoadableExampleModalPage} />
        <Route path={Routes.dev.examples.loadingPage} exact component={LoadableExampleLoadingPage} />
        <Route path={Routes.dev.examples.form} component={LoadableExampleFormPage} />
diff --git a/frontend/lib/hp-action.tsx b/frontend/lib/hp-action.tsx
index 729741dab..6e718889f 100644
--- a/frontend/lib/hp-action.tsx
+++ b/frontend/lib/hp-action.tsx
@@ -16,7 +16,7 @@ import { GetHPActionUploadStatus } from './queries/GetHPActionUploadStatus';
 import { Redirect } from 'react-router';
 import { SessionPoller } from './session-poller';
 
-const onboardingForHPActionRoute = Routes.hp.onboarding.latestStep;
+const onboardingForHPActionRoute = () => Routes.locale.hp.onboarding.latestStep;
 
 function HPActionSplash(): JSX.Element {
   return (
@@ -25,7 +25,7 @@ function HPActionSplash(): JSX.Element {
       <p>Welcome to JustFix.nyc! This website will guide you through the process of starting an <strong>HP Action</strong> proceeding.</p>
       <p>An <strong>HP Action</strong> is a legal case you can bring against your landlord for failing to make repairs, not providing essential services, or harassing you.</p>
       <p><em>This service is free, secure, and confidential.</em></p>
-      <CenteredPrimaryButtonLink className="is-large" to={onboardingForHPActionRoute}>
+      <CenteredPrimaryButtonLink className="is-large" to={onboardingForHPActionRoute()}>
         Start my case
       </CenteredPrimaryButtonLink>
     </Page>
@@ -48,7 +48,7 @@ const HPActionWelcome = withAppContext((props: AppContextType) => {
           <li><strong>Print out this packet and bring it to Housing Court.</strong> It will include instructions for <strong>filing in court</strong> and <strong>serving your landlord</strong>.
 </li>
         </ol>
-        <CenteredPrimaryButtonLink to={Routes.hp.issues.home}>
+        <CenteredPrimaryButtonLink to={Routes.locale.hp.issues.home}>
           Select repair issues
         </CenteredPrimaryButtonLink>
         <br/>
@@ -62,9 +62,9 @@ const HPActionWelcome = withAppContext((props: AppContextType) => {
 
 const HPActionIssuesRoutes = () => (
   <IssuesRoutes
-    routes={Routes.hp.issues}
-    toBack={Routes.hp.postOnboarding}
-    toNext={Routes.hp.yourLandlord}
+    routes={Routes.locale.hp.issues}
+    toBack={Routes.locale.hp.postOnboarding}
+    toNext={Routes.locale.hp.yourLandlord}
   />
 );
 
@@ -83,7 +83,7 @@ const LandlordDetails = (props: { details: AllSessionInfo_landlordDetails }) =>
 
 const GeneratePDFForm = (props: { children: FormContextRenderer<{}> }) => (
   <SessionUpdatingFormSubmitter mutation={GenerateHPActionPDFMutation} initialState={{}}
-   onSuccessRedirect={Routes.hp.waitForUpload} {...props} />
+   onSuccessRedirect={Routes.locale.hp.waitForUpload} {...props} />
 );
 
 const HPActionYourLandlord = withAppContext((props: AppContextType) => {
@@ -98,7 +98,7 @@ const HPActionYourLandlord = withAppContext((props: AppContextType) => {
       <GeneratePDFForm>
         {(ctx) =>
           <div className="buttons jf-two-buttons">
-            <BackButton to={Routes.hp.issues.home} label="Back" />
+            <BackButton to={Routes.locale.hp.issues.home} label="Back" />
             <NextButton isLoading={ctx.isLoading} label="Generate forms"/>
           </div>
         }
@@ -139,13 +139,13 @@ const ShowHPUploadStatus = withAppContext((props: AppContextType) => {
     return <HPActionWaitForUpload />;
 
     case HPUploadStatus.SUCCEEDED:
-    return <Redirect to={Routes.hp.confirmation} />;
+    return <Redirect to={Routes.locale.hp.confirmation} />;
 
     case HPUploadStatus.ERRORED:
     return <HPActionUploadError />;
 
     case HPUploadStatus.NOT_STARTED:
-    return <Redirect to={Routes.hp.latestStep} />;
+    return <Redirect to={Routes.locale.hp.latestStep} />;
   }
 });
 
@@ -174,27 +174,27 @@ const HPActionConfirmation = withAppContext((props: AppContextType) => {
   );
 });
 
-export const HPActionProgressRoutesProps: ProgressRoutesProps = {
-  toLatestStep: Routes.hp.latestStep,
+export const getHPActionProgressRoutesProps = (): ProgressRoutesProps => ({
+  toLatestStep: Routes.locale.hp.latestStep,
   label: "HP Action",
   welcomeSteps: [{
-    path: Routes.hp.splash, exact: true, component: HPActionSplash,
+    path: Routes.locale.hp.splash, exact: true, component: HPActionSplash,
     isComplete: (s) => !!s.phoneNumber
   }, {
-    path: Routes.hp.welcome, exact: true, component: HPActionWelcome
+    path: Routes.locale.hp.welcome, exact: true, component: HPActionWelcome
   }],
   stepsToFillOut: [
-    { path: Routes.hp.issues.prefix, component: HPActionIssuesRoutes },
-    { path: Routes.hp.yourLandlord, exact: true, component: HPActionYourLandlord,
+    { path: Routes.locale.hp.issues.prefix, component: HPActionIssuesRoutes },
+    { path: Routes.locale.hp.yourLandlord, exact: true, component: HPActionYourLandlord,
       isComplete: (s) => s.hpActionUploadStatus !== HPUploadStatus.NOT_STARTED },
   ],
   confirmationSteps: [
-    { path: Routes.hp.waitForUpload, exact: true, component: ShowHPUploadStatus,
+    { path: Routes.locale.hp.waitForUpload, exact: true, component: ShowHPUploadStatus,
       isComplete: (s) => s.hpActionUploadStatus === HPUploadStatus.SUCCEEDED },
-    { path: Routes.hp.confirmation, exact: true, component: HPActionConfirmation}
+    { path: Routes.locale.hp.confirmation, exact: true, component: HPActionConfirmation}
   ]
-};
+});
 
-const HPActionRoutes = buildProgressRoutesComponent(HPActionProgressRoutesProps);
+const HPActionRoutes = buildProgressRoutesComponent(getHPActionProgressRoutesProps);
 
 export default HPActionRoutes;
diff --git a/frontend/lib/i18n.ts b/frontend/lib/i18n.ts
new file mode 100644
index 000000000..c4a775e3c
--- /dev/null
+++ b/frontend/lib/i18n.ts
@@ -0,0 +1,103 @@
+/**
+ * This class keeps track of internationalization-related data.
+ * 
+ * Instances start out uninitialized, and must be explicitly
+ * initialized before any other methods or properties can be
+ * accessed.
+ * 
+ * Once initialized, an instance can actually be re-initialized;
+ * clients can register to be notified if and when this happens.
+ */
+export class I18n {
+  private _locale: null|string = null;
+  private _changeListeners: Function[] = [];
+
+  /**
+   * Create an instance, optionally auto-initializing it.
+   * 
+   * @param locale An empty string to indicate that localization is
+   *   disabled, or an ISO 639-1 code such as 'en' or 'es'.
+   */
+  constructor(locale?: string) {
+    if (typeof(locale) === 'string') {
+      this.initialize(locale);
+    }
+  }
+
+  private raiseInitError(): never {
+    throw new Error('i18n is not initialized!');
+  }
+
+  /**
+   * Return the current locale, raising an error if the
+   * class is uninitialized.
+   * 
+   * If the locale is set to the empty string, it means that
+   * localization is currently disabled. Otherwise, the
+   * string will be an ISO 639-1 code such as 'en' or 'es'.
+   */
+  get locale(): string {
+    if (this._locale === null) return this.raiseInitError();
+    return this._locale;
+  }
+
+  /**
+   * Return the URL path prefix for the current locale.
+   * If localization is disabled, this will be the
+   * empty string; otherwise, it will be a slash followed
+   * by the locale's ISO 639-1 code, e.g. '/en'.
+   */
+  get localePathPrefix(): string {
+    const { locale } = this;
+    return locale === '' ? '' : `/${locale}`;
+  }
+
+  /**
+   * Initialize the instance to the given locale.
+   * 
+   * @param locale An empty string to indicate that localization is
+   *   disabled, or an ISO 639-1 code such as 'en' or 'es'.
+   */
+  initialize(locale: string) {
+    this._locale = locale;
+    this._changeListeners.forEach(cb => cb());
+  }
+
+  /** Return whether the instance is initialized. */
+  get isInitialized(): boolean {
+    return this._locale !== null;
+  }
+
+  /**
+   * Register a listener to be notified when the instance
+   * is initialized or re-initialized.
+   */
+  addChangeListener(cb: Function) {
+    this._changeListeners.push(cb);
+  }
+
+  /** Unregister a previously-registered listener. */
+  removeChangeListener(cb: Function) {
+    const index = this._changeListeners.indexOf(cb);
+    if (index === -1) {
+      throw new Error('change listener does not exist!');
+    }
+    this._changeListeners.splice(index, 1);
+  }
+}
+
+/**
+ * This is a global singleton for the JS runtime. It's largely
+ * a singleton because passing it around everywhere would be
+ * a massive headache, especially given the state of the codebase
+ * at the time that internationalization was introduced.
+ * 
+ * That said, one should prefer to write client code in a way
+ * such that an I18n object is passed into it, rather than
+ * grabbing this singleton directly. This will make it easier
+ * to unit test, as well as to eventually get rid of the global
+ * singleton altogether.
+ */
+const i18n = new I18n();
+
+export default i18n;
diff --git a/frontend/lib/letter-of-complaint.tsx b/frontend/lib/letter-of-complaint.tsx
index 10c24337b..2c5c27972 100644
--- a/frontend/lib/letter-of-complaint.tsx
+++ b/frontend/lib/letter-of-complaint.tsx
@@ -24,7 +24,7 @@ export const Welcome = withAppContext((props: AppContextType): JSX.Element => {
           <li>First, conduct a <strong>self-inspection of your apartment</strong> to document all the issues that need repair.</li>
           <li>Review your Letter of Complaint and JustFix.nyc will send it to your landlord via USPS Certified Mail<sup>&reg;</sup>.</li>
         </ol>
-        <CenteredPrimaryButtonLink to={Routes.loc.issues.home}>
+        <CenteredPrimaryButtonLink to={Routes.locale.loc.issues.home}>
           Start my free letter
         </CenteredPrimaryButtonLink>
         <br/>
@@ -42,30 +42,30 @@ export const Welcome = withAppContext((props: AppContextType): JSX.Element => {
 
 const LetterOfComplaintIssuesRoutes = () => (
   <IssuesRoutes
-    routes={Routes.loc.issues}
-    toBack={Routes.loc.home}
-    toNext={Routes.loc.accessDates}
+    routes={Routes.locale.loc.issues}
+    toBack={Routes.locale.loc.home}
+    toNext={Routes.locale.loc.accessDates}
   />
 );
 
-export const LOCProgressRoutesProps: ProgressRoutesProps = {
-  toLatestStep: Routes.loc.latestStep,
+export const getLOCProgressRoutesProps = (): ProgressRoutesProps => ({
+  toLatestStep: Routes.locale.loc.latestStep,
   label: "Letter of Complaint",
   welcomeSteps: [{
-    path: Routes.loc.home, exact: true, component: Welcome
+    path: Routes.locale.loc.home, exact: true, component: Welcome
   }],
   stepsToFillOut: [
-    { path: Routes.loc.issues.prefix, component: LetterOfComplaintIssuesRoutes },
-    { path: Routes.loc.accessDates, exact: true, component: AccessDatesPage },
-    { path: Routes.loc.yourLandlord, exact: true, component: LandlordDetailsPage },
-    { path: Routes.loc.preview, component: LetterRequestPage,
+    { path: Routes.locale.loc.issues.prefix, component: LetterOfComplaintIssuesRoutes },
+    { path: Routes.locale.loc.accessDates, exact: true, component: AccessDatesPage },
+    { path: Routes.locale.loc.yourLandlord, exact: true, component: LandlordDetailsPage },
+    { path: Routes.locale.loc.preview, component: LetterRequestPage,
       isComplete: sess => !!sess.letterRequest },
   ],
   confirmationSteps: [{
-    path: Routes.loc.confirmation, exact: true, component: LetterConfirmation
+    path: Routes.locale.loc.confirmation, exact: true, component: LetterConfirmation
   }]
-};
+});
 
-const LetterOfComplaintRoutes = buildProgressRoutesComponent(LOCProgressRoutesProps);
+const LetterOfComplaintRoutes = buildProgressRoutesComponent(getLOCProgressRoutesProps);
 
 export default LetterOfComplaintRoutes;
diff --git a/frontend/lib/main.ts b/frontend/lib/main.ts
index 35db5268a..fbdda7ca3 100644
--- a/frontend/lib/main.ts
+++ b/frontend/lib/main.ts
@@ -3,6 +3,7 @@
 import { startApp, AppProps } from './app';
 import { getElement } from './util';
 import { ga } from './google-analytics';
+import i18n from './i18n';
 
 
 function polyfillSmoothScroll() {
@@ -46,6 +47,7 @@ window.addEventListener('load', () => {
   // Since JS is now loaded, let's remove that restriction.
   div.removeAttribute('hidden');
 
+  i18n.initialize(initialProps.locale);
   startApp(div, initialProps);
   polyfillSmoothScroll();
   showSafeModeUiOnShake();
diff --git a/frontend/lib/navbar.tsx b/frontend/lib/navbar.tsx
index 0a5498fde..1d8c7587e 100644
--- a/frontend/lib/navbar.tsx
+++ b/frontend/lib/navbar.tsx
@@ -118,7 +118,7 @@ class NavbarWithoutAppContext extends React.Component<NavbarProps, NavbarState>
 
     return (
       <div className="navbar-brand">
-        <Link className="navbar-item" to={Routes.home}>
+        <Link className="navbar-item" to={Routes.locale.home}>
           <StaticImage src="frontend/img/logo.png" alt="Home" />
         </Link>
         <AriaExpandableButton
@@ -147,8 +147,8 @@ class NavbarWithoutAppContext extends React.Component<NavbarProps, NavbarState>
             <div className="navbar-end">
               {session.isStaff && <a className="navbar-item" href={server.adminIndexURL}>Admin</a>}
               {session.phoneNumber
-                ? <Link className="navbar-item" to={Routes.logout}>Sign out</Link>
-                : <Link className="navbar-item" to={Routes.login}>Sign in</Link> }
+                ? <Link className="navbar-item" to={Routes.locale.logout}>Sign out</Link>
+                : <Link className="navbar-item" to={Routes.locale.login}>Sign in</Link> }
               {this.renderDevMenu()}
             </div>
           </div>
diff --git a/frontend/lib/pages/access-dates.tsx b/frontend/lib/pages/access-dates.tsx
index 9ec53a555..8e39a5709 100644
--- a/frontend/lib/pages/access-dates.tsx
+++ b/frontend/lib/pages/access-dates.tsx
@@ -36,7 +36,7 @@ function renderForm(ctx: FormContext<AccessDatesInput>): JSX.Element {
       <TextualFormField label="Second access date (optional)" type="date" min={minDate} {...ctx.fieldPropsFor('date2')} />
       <TextualFormField label="Third access date (optional)" type="date" min={minDate} {...ctx.fieldPropsFor('date3')} />
       <div className="buttons jf-two-buttons">
-        <BackButton to={Routes.loc.issues.home} label="Back" />
+        <BackButton to={Routes.locale.loc.issues.home} label="Back" />
         <NextButton isLoading={ctx.isLoading} />
       </div>
     </React.Fragment>
@@ -52,7 +52,7 @@ export default function AccessDatesPage(): JSX.Element {
         <SessionUpdatingFormSubmitter
           mutation={AccessDatesMutation}
           initialState={(session) => getInitialState(session.accessDates)}
-          onSuccessRedirect={Routes.loc.yourLandlord}
+          onSuccessRedirect={Routes.locale.loc.yourLandlord}
         >
           {renderForm}
         </SessionUpdatingFormSubmitter>
diff --git a/frontend/lib/pages/example-form-page.tsx b/frontend/lib/pages/example-form-page.tsx
index 8879e9810..39f8d2281 100644
--- a/frontend/lib/pages/example-form-page.tsx
+++ b/frontend/lib/pages/example-form-page.tsx
@@ -71,7 +71,7 @@ export default function ExampleFormPage(): JSX.Element {
           Use the form in a modal
         </ModalLink>
       </div>
-      <ExampleForm onSuccessRedirect={Routes.home} id="not_in_modal" />
+      <ExampleForm onSuccessRedirect={Routes.locale.home} id="not_in_modal" />
     </Page>
   );
 }
diff --git a/frontend/lib/pages/index-page.tsx b/frontend/lib/pages/index-page.tsx
index 7b7e34aba..c32cc07c3 100644
--- a/frontend/lib/pages/index-page.tsx
+++ b/frontend/lib/pages/index-page.tsx
@@ -13,7 +13,7 @@ export interface IndexPageProps {
   isLoggedIn: boolean;
 }
 
-const onboardingForLOCRoute = Routes.onboarding.latestStep;
+const onboardingForLOCRoute = () => Routes.locale.onboarding.latestStep;
 
 export default class IndexPage extends React.Component<IndexPageProps> {
   renderLoggedOut() {
@@ -32,10 +32,10 @@ export default class IndexPage extends React.Component<IndexPageProps> {
               <h2 className="subtitle">
                 JustFix.nyc is a free tool that notifies your landlord of repair issues via <b>USPS Certified Mail<sup>&reg;</sup></b>. Everything is documented, confidential, and secure.
               </h2>
-              <CenteredPrimaryButtonLink to={onboardingForLOCRoute} className="is-large">
+              <CenteredPrimaryButtonLink to={onboardingForLOCRoute()} className="is-large">
                 Start my free letter
               </CenteredPrimaryButtonLink>
-              <p className="secondary-cta">Already have an account? <Link to={Routes.login}>Sign in!</Link></p>
+              <p className="secondary-cta">Already have an account? <Link to={Routes.locale.login}>Sign in!</Link></p>
             </div>
           </div>
         </section>
@@ -69,7 +69,7 @@ export default class IndexPage extends React.Component<IndexPageProps> {
                 </div>
               </div>
             </div>
-            <CenteredPrimaryButtonLink to={onboardingForLOCRoute} className="is-large">
+            <CenteredPrimaryButtonLink to={onboardingForLOCRoute()} className="is-large">
               Start my free letter
             </CenteredPrimaryButtonLink>
           </div>
diff --git a/frontend/lib/pages/landlord-details.tsx b/frontend/lib/pages/landlord-details.tsx
index fce34aa8a..3a3724ada 100644
--- a/frontend/lib/pages/landlord-details.tsx
+++ b/frontend/lib/pages/landlord-details.tsx
@@ -19,9 +19,9 @@ const BLANK_INPUT: LandlordDetailsInput = {
   address: ''
 };
 
-const PREV_STEP = Routes.loc.accessDates;
+const PREV_STEP = () => Routes.locale.loc.accessDates;
 
-const NEXT_STEP = Routes.loc.preview;
+const NEXT_STEP = () => Routes.locale.loc.preview;
 
 function renderForm(ctx: FormContext<LandlordDetailsInput>): JSX.Element {
   return (
@@ -29,7 +29,7 @@ function renderForm(ctx: FormContext<LandlordDetailsInput>): JSX.Element {
       <TextualFormField label="Landlord's name" type="text" {...ctx.fieldPropsFor('name')} />
       <TextareaFormField label="Landlord's address" {...ctx.fieldPropsFor('address')} />
       <div className="buttons jf-two-buttons">
-        <BackButton to={PREV_STEP} label="Back" />
+        <BackButton to={PREV_STEP()} label="Back" />
         <NextButton isLoading={ctx.isLoading} label="Preview letter" />
       </div>
     </React.Fragment>
@@ -68,8 +68,8 @@ function ReadOnlyLandlordDetails(props: {details: AllSessionInfo_landlordDetails
         <dd>{splitLines(details.address)}</dd>
       </dl>
       <div className="buttons jf-two-buttons">
-        <BackButton to={PREV_STEP} label="Back" />
-        <Link to={NEXT_STEP} className="button is-primary is-medium">Preview letter</Link>
+        <BackButton to={PREV_STEP()} label="Back" />
+        <Link to={NEXT_STEP()} className="button is-primary is-medium">Preview letter</Link>
       </div>
     </div>
   );
diff --git a/frontend/lib/pages/letter-request.tsx b/frontend/lib/pages/letter-request.tsx
index 1308d4999..a49c7c6a2 100644
--- a/frontend/lib/pages/letter-request.tsx
+++ b/frontend/lib/pages/letter-request.tsx
@@ -56,7 +56,7 @@ function FormAsButton(props: FormAsButtonProps): JSX.Element {
       mutation={LetterRequestMutation}
       formId={'button_' + props.mailChoice}
       initialState={input}
-      onSuccessRedirect={Routes.loc.confirmation}
+      onSuccessRedirect={Routes.locale.loc.confirmation}
     >
       {(ctx) => <>
         <HiddenFormField {...ctx.fieldPropsFor('mailChoice')} />
@@ -79,11 +79,11 @@ export default function LetterRequestPage(): JSX.Element {
       <p className="subtitle is-6">Here is a preview of the letter for you to review. It includes the repair issues you selected from the Issue Checklist.</p>
       <LetterPreview />
       <div className="has-text-centered is-grouped">
-        <ModalLink to={Routes.loc.previewSendConfirmModal} component={SendConfirmModal} className="button is-primary is-medium">
+        <ModalLink to={Routes.locale.loc.previewSendConfirmModal} component={SendConfirmModal} className="button is-primary is-medium">
           Looks good to me!
         </ModalLink>
         <div className="buttons jf-two-buttons jf-two-buttons--vertical">
-          <BackButton to={Routes.loc.yourLandlord} buttonClass="is-text" label="Go back and edit" />
+          <BackButton to={Routes.locale.loc.yourLandlord} buttonClass="is-text" label="Go back and edit" />
           <FormAsButton
             mailChoice={LetterRequestMailChoice.USER_WILL_MAIL}
             buttonClass="is-text"
diff --git a/frontend/lib/pages/login-page.tsx b/frontend/lib/pages/login-page.tsx
index 20607a472..d7fc84585 100644
--- a/frontend/lib/pages/login-page.tsx
+++ b/frontend/lib/pages/login-page.tsx
@@ -90,7 +90,7 @@ export function absolutifyURLToOurOrigin(url: string, origin: string): string {
 
 const LoginPage = withAppContext((props: RouteComponentProps<any> & AppContextType): JSX.Element => {
   let next = absolutifyURLToOurOrigin(
-    getPostOrQuerystringVar(props, NEXT) || Routes.home,
+    getPostOrQuerystringVar(props, NEXT) || Routes.locale.home,
     props.server.originURL
   );
 
diff --git a/frontend/lib/pages/logout-page.tsx b/frontend/lib/pages/logout-page.tsx
index 6337b8dbb..4dc31e63d 100644
--- a/frontend/lib/pages/logout-page.tsx
+++ b/frontend/lib/pages/logout-page.tsx
@@ -19,7 +19,7 @@ export const LogoutPage = withAppContext((props: AppContextType) => {
             mutation={LogoutMutation}
             initialState={{}}
             // This looks odd but it's required for legacy POST to work.
-            onSuccessRedirect={Routes.logout}
+            onSuccessRedirect={Routes.locale.logout}
           >{(ctx) => (
               <NextButton isLoading={ctx.isLoading} label="Yes, sign out" />
           )}</SessionUpdatingFormSubmitter>
@@ -30,7 +30,7 @@ export const LogoutPage = withAppContext((props: AppContextType) => {
     return (
       <Page title="Signed out">
         <h1 className="title">You are now signed out.</h1>
-        <p><Link to={Routes.login}>Sign back in</Link></p>
+        <p><Link to={Routes.locale.login}>Sign back in</Link></p>
       </Page>
     );
   }
diff --git a/frontend/lib/progress-routes.tsx b/frontend/lib/progress-routes.tsx
index 3dfd21d61..73ac08b33 100644
--- a/frontend/lib/progress-routes.tsx
+++ b/frontend/lib/progress-routes.tsx
@@ -78,6 +78,6 @@ export function ProgressRoutes(props: ProgressRoutesProps): JSX.Element {
   );
 }
 
-export function buildProgressRoutesComponent(props: ProgressRoutesProps): () => JSX.Element {
-  return () => <ProgressRoutes {...props}/>;
+export function buildProgressRoutesComponent(getProps: () => ProgressRoutesProps): () => JSX.Element {
+  return () => <ProgressRoutes {...getProps()}/>;
 }
diff --git a/frontend/lib/routes.ts b/frontend/lib/routes.ts
index bf2555438..d21506476 100644
--- a/frontend/lib/routes.ts
+++ b/frontend/lib/routes.ts
@@ -1,5 +1,6 @@
 import { matchPath, RouteComponentProps } from 'react-router-dom';
 import { OnboardingInfoSignupIntent } from './queries/globalTypes';
+import i18n from './i18n';
 
 /**
  * Metadata about signup intents.
@@ -23,12 +24,12 @@ type SignupIntentOnboardingInfo = {
 export function getSignupIntentOnboardingInfo(intent: OnboardingInfoSignupIntent): SignupIntentOnboardingInfo {
   switch (intent) {
     case OnboardingInfoSignupIntent.LOC: return {
-      preOnboarding: Routes.home,
-      postOnboarding: Routes.loc.latestStep,
-      onboarding: Routes.onboarding
+      preOnboarding: Routes.locale.home,
+      postOnboarding: Routes.locale.loc.latestStep,
+      onboarding: Routes.locale.onboarding
     };
 
-    case OnboardingInfoSignupIntent.HP: return Routes.hp;
+    case OnboardingInfoSignupIntent.HP: return Routes.locale.hp;
   }
 }
 
@@ -87,12 +88,79 @@ function createOnboardingRouteInfo(prefix: string) {
   };
 }
 
+export type LetterOfComplaintInfo = ReturnType<typeof createLetterOfComplaintRouteInfo>;
+
+function createLetterOfComplaintRouteInfo(prefix: string) {
+  return {
+    [ROUTE_PREFIX]: prefix,
+    latestStep: prefix,
+    home: `${prefix}/welcome`,
+    issues: createIssuesRouteInfo(`${prefix}/issues`),
+    accessDates: `${prefix}/access-dates`,
+    yourLandlord: `${prefix}/your-landlord`,
+    preview: `${prefix}/preview`,
+    previewSendConfirmModal: `${prefix}/preview/send-confirm-modal`,
+    confirmation: `${prefix}/confirmation`
+  };
+}
+
+export type HPActionInfo = ReturnType<typeof createHPActionRouteInfo>;
+
+function createHPActionRouteInfo(prefix: string) {
+  return {
+    [ROUTE_PREFIX]: prefix,
+    latestStep: prefix,
+    preOnboarding: `${prefix}/splash`,
+    splash: `${prefix}/splash`,
+    onboarding: createOnboardingRouteInfo(`${prefix}/onboarding`),
+    postOnboarding: prefix,
+    welcome: `${prefix}/welcome`,
+    issues: createIssuesRouteInfo(`${prefix}/issues`),
+    yourLandlord: `${prefix}/your-landlord`,
+    waitForUpload: `${prefix}/wait`,
+    confirmation: `${prefix}/confirmation`,
+  }
+}
+
+export type LocalizedRouteInfo = ReturnType<typeof createLocalizedRouteInfo>;
+
+function createLocalizedRouteInfo(prefix: string) {
+  return {
+    /** The login page. */
+    login: `${prefix}/login`,
+
+    /** The logout page. */
+    logout: `${prefix}/logout`,
+
+    /** The home page. */
+    home: `${prefix}/`,
+
+    /** The onboarding flow. */
+    onboarding: createOnboardingRouteInfo(`${prefix}/onboarding`),
+
+    /** The Letter of Complaint flow. */
+    loc: createLetterOfComplaintRouteInfo(`${prefix}/loc`),
+
+    /** The HP Action flow. */
+    hp: createHPActionRouteInfo(`${prefix}/hp`),
+  }
+}
+
+let currentLocaleRoutes: LocalizedRouteInfo|null = null;
+
+i18n.addChangeListener(() => { currentLocaleRoutes = null; });
+
 /**
  * This is an ad-hoc structure that defines URL routes for our app.
  */
 const Routes = {
-  /** The login page. */
-  login: '/login',
+  /** Localized routes for the user's currently-selected locale. */
+  get locale(): LocalizedRouteInfo {
+    if (currentLocaleRoutes === null) {
+      currentLocaleRoutes = createLocalizedRouteInfo(i18n.localePathPrefix);
+    }
+    return currentLocaleRoutes;
+  },
 
   /**
    * The *admin* login page. We override Django's default admin login
@@ -101,50 +169,13 @@ const Routes = {
    */
   adminLogin: '/admin/login/',
 
-  /** The logout page. */
-  logout: '/logout',
-
-  /** The home page. */
-  home: '/',
-
-  /** The onboarding flow. */
-  onboarding: createOnboardingRouteInfo('/onboarding'),
-
-  /** The Letter of Complaint flow. */
-  loc: {
-    [ROUTE_PREFIX]: '/loc',
-    latestStep: '/loc',
-    home: '/loc/welcome',
-    issues: createIssuesRouteInfo('/loc/issues'),
-    accessDates: '/loc/access-dates',
-    yourLandlord: '/loc/your-landlord',
-    preview: '/loc/preview',
-    previewSendConfirmModal: '/loc/preview/send-confirm-modal',
-    confirmation: '/loc/confirmation'
-  },
-
-  /** The HP Action flow. */
-  hp: {
-    [ROUTE_PREFIX]: '/hp',
-    latestStep: '/hp',
-    preOnboarding: '/hp/splash',
-    splash: '/hp/splash',
-    onboarding: createOnboardingRouteInfo('/hp/onboarding'),
-    postOnboarding: '/hp',
-    welcome: '/hp/welcome',
-    issues: createIssuesRouteInfo('/hp/issues'),
-    yourLandlord: '/hp/your-landlord',
-    waitForUpload: '/hp/wait',
-    confirmation: '/hp/confirmation',
-  },
-
   /**
    * Example pages used in integration tests, and other
    * development-related pages.
    */
   dev: {
     [ROUTE_PREFIX]: '/dev',
-    home: '/dev',
+    home: '/dev/',
     examples: {
       [ROUTE_PREFIX]: '/dev/examples',
       redirect: '/dev/examples/redirect',
@@ -186,9 +217,16 @@ export function isParameterizedRoute(path: string): boolean {
 export class RouteMap {
   private existenceMap: Map<string, boolean> = new Map();
   private parameterizedRoutes: string[] = [];
+  private isInitialized = false;
+
+  constructor(private readonly routes: any) {
+  }
 
-  constructor(routes: any) {
-    this.populate(routes);
+  private ensureIsInitialized() {
+    if (!this.isInitialized) {
+      this.populate(this.routes);
+      this.isInitialized = true;
+    }
   }
 
   private populate(routes: any) {
@@ -207,6 +245,7 @@ export class RouteMap {
   }
 
   get size(): number {
+    this.ensureIsInitialized();
     return this.existenceMap.size + this.parameterizedRoutes.length;
   }
 
@@ -214,6 +253,7 @@ export class RouteMap {
    * Return an iterator that yields all routes that don't have parameters.
    */
   nonParameterizedRoutes(): IterableIterator<string> {
+    this.ensureIsInitialized();
     return this.existenceMap.keys();
   }
 
@@ -228,6 +268,7 @@ export class RouteMap {
    * further down the view heirarchy to resolve.
    */
   exists(pathname: string): boolean {
+    this.ensureIsInitialized();
     if (this.existenceMap.has(pathname)) {
       return true;
     }
diff --git a/frontend/lib/tests/app.test.tsx b/frontend/lib/tests/app.test.tsx
index ceab64c23..381efea99 100644
--- a/frontend/lib/tests/app.test.tsx
+++ b/frontend/lib/tests/app.test.tsx
@@ -9,6 +9,7 @@ describe('AppWithoutRouter', () => {
     const { client } = createTestGraphQlClient();
     const props: AppPropsWithRouter = {
       initialURL: '/',
+      locale: '',
       initialSession: FakeSessionInfo,
       server: FakeServerInfo,
       history: {} as any,
diff --git a/frontend/lib/tests/hp-action.test.tsx b/frontend/lib/tests/hp-action.test.tsx
index ee197211a..2679c0e69 100644
--- a/frontend/lib/tests/hp-action.test.tsx
+++ b/frontend/lib/tests/hp-action.test.tsx
@@ -1,12 +1,12 @@
 import React from 'react';
 
 import { AppTesterPal } from "./app-tester-pal";
-import HPActionRoutes, { HPActionProgressRoutesProps } from '../hp-action';
+import HPActionRoutes, { getHPActionProgressRoutesProps } from '../hp-action';
 import { ProgressRoutesTester } from './progress-routes-tester';
 import Routes from '../routes';
 import { HPUploadStatus } from '../queries/globalTypes';
 
-const tester = new ProgressRoutesTester(HPActionProgressRoutesProps, 'HP Action');
+const tester = new ProgressRoutesTester(getHPActionProgressRoutesProps(), 'HP Action');
 
 tester.defineSmokeTests();
 
@@ -57,23 +57,23 @@ describe('upload status page', () => {
 
 describe('latest step redirector', () => {
   it('returns splash page when user is not logged-in', () => {
-    expect(tester.getLatestStep()).toBe(Routes.hp.splash);
+    expect(tester.getLatestStep()).toBe(Routes.locale.hp.splash);
   });
 
   it('returns welcome page when user is logged-in', () => {
-    expect(tester.getLatestStep({ phoneNumber: '123' })).toBe(Routes.hp.welcome);
+    expect(tester.getLatestStep({ phoneNumber: '123' })).toBe(Routes.locale.hp.welcome);
   });
 
   it('returns wait page when user has started document assembly', () => {
     expect(tester.getLatestStep({
       hpActionUploadStatus: HPUploadStatus.STARTED
-    })).toBe(Routes.hp.waitForUpload);
+    })).toBe(Routes.locale.hp.waitForUpload);
   });
 
   it('returns confirmation page when user has generated a PDF', () => {
     expect(tester.getLatestStep({
       latestHpActionPdfUrl: '/boop.pdf',
       hpActionUploadStatus: HPUploadStatus.SUCCEEDED
-    })).toBe(Routes.hp.confirmation);
+    })).toBe(Routes.locale.hp.confirmation);
   });
 });
diff --git a/frontend/lib/tests/i18n.test.ts b/frontend/lib/tests/i18n.test.ts
new file mode 100644
index 000000000..34d06566d
--- /dev/null
+++ b/frontend/lib/tests/i18n.test.ts
@@ -0,0 +1,45 @@
+import { I18n } from "../i18n";
+
+const UNINIT_RE = /i18n is not initialized/i;
+
+describe('I18n', () => {
+  it('raises exception on methods/properties if uninitialized', () => {
+    const i18n = new I18n();
+    expect(() => i18n.locale).toThrow(UNINIT_RE);
+    expect(() => i18n.localePathPrefix).toThrow(UNINIT_RE);
+  });
+
+  it('returns whether it is initialized or not', () => {
+    expect(new I18n('en').isInitialized).toBe(true);
+
+    const i18n = new I18n();
+    expect(i18n.isInitialized).toBe(false);
+    i18n.initialize('en');
+    expect(i18n.isInitialized).toBe(true);
+  });
+
+  it('raises error if nonexistent listener is removed', () => {
+    expect(() => new I18n().removeChangeListener(() => {}))
+      .toThrow(/change listener does not exist/i);
+  });
+
+  it('notifies listeners on initialization', () => {
+    let calls = 0;
+    const i18n = new I18n();
+    const cb = () => calls++;
+    i18n.addChangeListener(cb);
+    expect(calls).toBe(0);
+    i18n.initialize('en');
+    expect(calls).toBe(1);
+    i18n.initialize('es');
+    expect(calls).toBe(2);
+    i18n.removeChangeListener(cb);
+    i18n.initialize('de');
+    expect(calls).toBe(2);
+  });
+
+  it('returns locale path prefixes', () => {
+    expect(new I18n('').localePathPrefix).toBe('');
+    expect(new I18n('en').localePathPrefix).toBe('/en');
+  });
+});
diff --git a/frontend/lib/tests/letter-of-complaint.test.tsx b/frontend/lib/tests/letter-of-complaint.test.tsx
index 8d42202b1..e3d777d65 100644
--- a/frontend/lib/tests/letter-of-complaint.test.tsx
+++ b/frontend/lib/tests/letter-of-complaint.test.tsx
@@ -1,19 +1,19 @@
-import { LOCProgressRoutesProps } from '../letter-of-complaint';
+import { getLOCProgressRoutesProps } from '../letter-of-complaint';
 import Routes from '../routes';
 import { ProgressRoutesTester } from './progress-routes-tester';
 
-const tester = new ProgressRoutesTester(LOCProgressRoutesProps, 'letter of complaint');
+const tester = new ProgressRoutesTester(getLOCProgressRoutesProps(), 'letter of complaint');
 
 tester.defineSmokeTests();
 
 describe('latest step redirector', () => {
   it('returns welcome page by default', () => {
-    expect(tester.getLatestStep()).toBe(Routes.loc.home);
+    expect(tester.getLatestStep()).toBe(Routes.locale.loc.home);
   });
 
   it('returns confirmation page if letter request has been submitted', () => {
     expect(tester.getLatestStep({
       letterRequest: {} as any
-    })).toBe(Routes.loc.confirmation);
+    })).toBe(Routes.locale.loc.confirmation);
   });
 });
diff --git a/frontend/lib/tests/onboarding.test.tsx b/frontend/lib/tests/onboarding.test.tsx
index 5a4110dc6..058451195 100644
--- a/frontend/lib/tests/onboarding.test.tsx
+++ b/frontend/lib/tests/onboarding.test.tsx
@@ -11,7 +11,7 @@ import { OnboardingInfoSignupIntent } from '../queries/globalTypes';
 const PROPS: OnboardingRoutesProps = {
   toCancel: '/cancel',
   toSuccess: '/success',
-  routes: Routes.onboarding,
+  routes: Routes.locale.onboarding,
   signupIntent: OnboardingInfoSignupIntent.LOC
 };
 
@@ -22,14 +22,14 @@ describe('latest step redirector', () => {
   }
 
   it('returns step 1 by default', () => {
-    expect(getLatestOnboardingStep(FakeSessionInfo)).toBe(Routes.onboarding.step1);
+    expect(getLatestOnboardingStep(FakeSessionInfo)).toBe(Routes.locale.onboarding.step1);
   });
 
   it('returns step 2 when step 1 is complete', () => {
     expect(getLatestOnboardingStep({
       ...FakeSessionInfo,
       onboardingStep1: {} as any
-    })).toBe(Routes.onboarding.step2);
+    })).toBe(Routes.locale.onboarding.step2);
   });
 
   it('returns step 3 when step 2 is complete', () => {
@@ -37,7 +37,7 @@ describe('latest step redirector', () => {
       ...FakeSessionInfo,
       onboardingStep1: {} as any,
       onboardingStep2: {} as any
-    })).toBe(Routes.onboarding.step3);
+    })).toBe(Routes.locale.onboarding.step3);
   });
 
   it('returns step 4 when step 3 is complete', () => {
@@ -46,7 +46,7 @@ describe('latest step redirector', () => {
       onboardingStep1: {} as any,
       onboardingStep2: {} as any,
       onboardingStep3: {} as any
-    })).toBe(Routes.onboarding.step4);
+    })).toBe(Routes.locale.onboarding.step4);
   });
 });
 
@@ -55,7 +55,7 @@ describe('Onboarding', () => {
 
   it('redirects to latest step', () => {
     const pal = new AppTesterPal(<OnboardingRoutes {...PROPS} />, {
-      url: Routes.onboarding.latestStep
+      url: Routes.locale.onboarding.latestStep
     });
     expect(pal.history.location.pathname).toEqual('/onboarding/step/1');
     pal.rr.getByLabelText('First name');
diff --git a/frontend/lib/tests/pages/access-dates.test.tsx b/frontend/lib/tests/pages/access-dates.test.tsx
index 58c8c5fa6..9e41c7bb2 100644
--- a/frontend/lib/tests/pages/access-dates.test.tsx
+++ b/frontend/lib/tests/pages/access-dates.test.tsx
@@ -12,7 +12,7 @@ describe('access dates page', () => {
 
   it('redirects to next step after successful submission', async () => {
     const pal = new AppTesterPal(<LetterOfComplaintRoutes/>, {
-      url: Routes.loc.accessDates
+      url: Routes.locale.loc.accessDates
     });
 
     pal.fillFormFields([
diff --git a/frontend/lib/tests/pages/index-page.test.tsx b/frontend/lib/tests/pages/index-page.test.tsx
index a94ff11e9..222bbc0f8 100644
--- a/frontend/lib/tests/pages/index-page.test.tsx
+++ b/frontend/lib/tests/pages/index-page.test.tsx
@@ -5,7 +5,7 @@ import Routes from '../../routes';
 
 describe('index page', () => {
   it('renders when logged in', () => {
-    ensureRedirect(<IndexPage isLoggedIn={true} />, Routes.loc.latestStep);
+    ensureRedirect(<IndexPage isLoggedIn={true} />, Routes.locale.loc.latestStep);
   });
 
   it('renders when logged out', () => {
diff --git a/frontend/lib/tests/pages/issue-pages.test.tsx b/frontend/lib/tests/pages/issue-pages.test.tsx
index 6fb804f66..9e8375743 100644
--- a/frontend/lib/tests/pages/issue-pages.test.tsx
+++ b/frontend/lib/tests/pages/issue-pages.test.tsx
@@ -9,10 +9,10 @@ import ISSUE_AREA_SVGS from '../../svg/issues';
 import { IssueAreaChoices } from '../../../../common-data/issue-area-choices';
 
 
-const routes = Routes.loc.issues;
+const routes = Routes.locale.loc.issues;
 
 const TestIssuesRoutes = () => 
-  <IssuesRoutes routes={Routes.loc.issues} toBack="back" toNext="next"/>;
+  <IssuesRoutes routes={Routes.locale.loc.issues} toBack="back" toNext="next"/>;
 
 describe('issues checklist', () => {
   afterEach(AppTesterPal.cleanup);
diff --git a/frontend/lib/tests/pages/landlord-details.test.tsx b/frontend/lib/tests/pages/landlord-details.test.tsx
index abbc0e412..5611606b8 100644
--- a/frontend/lib/tests/pages/landlord-details.test.tsx
+++ b/frontend/lib/tests/pages/landlord-details.test.tsx
@@ -24,7 +24,7 @@ describe('landlord details page', () => {
 
   it('works when details are not looked up', () => {
     const pal = new AppTesterPal(<LetterOfComplaintRoutes />, {
-      url: Routes.loc.yourLandlord,
+      url: Routes.locale.loc.yourLandlord,
       session: { landlordDetails: BLANK_LANDLORD_DETAILS }
     });
     pal.rr.getByText(/Please enter your landlord's name/i);
@@ -34,7 +34,7 @@ describe('landlord details page', () => {
 
   it('works when details are looked up', () => {
     const pal = new AppTesterPal(<LetterOfComplaintRoutes />, {
-      url: Routes.loc.yourLandlord,
+      url: Routes.locale.loc.yourLandlord,
       session: { landlordDetails: LOOKED_UP_LANDLORD_DETAILS }
     });
     pal.rr.getByText(/This may be different .+ rent checks/i);
@@ -44,7 +44,7 @@ describe('landlord details page', () => {
 
   it('redirects to next step after successful submission', async () => {
     const pal = new AppTesterPal(<LetterOfComplaintRoutes />, {
-      url: Routes.loc.yourLandlord,
+      url: Routes.locale.loc.yourLandlord,
       session: { landlordDetails: BLANK_LANDLORD_DETAILS }
     });
     const name = "Boop Jones";
diff --git a/frontend/lib/tests/pages/letter-request.test.tsx b/frontend/lib/tests/pages/letter-request.test.tsx
index 9e2bd3cf8..b7e00da84 100644
--- a/frontend/lib/tests/pages/letter-request.test.tsx
+++ b/frontend/lib/tests/pages/letter-request.test.tsx
@@ -31,7 +31,7 @@ describe('landlord details page', () => {
 
   it('works when user chooses to mail the letter themselves', async () => {
     const pal = new AppTesterPal(<LetterOfComplaintRoutes />, {
-      url: Routes.loc.preview,
+      url: Routes.locale.loc.preview,
       session: { letterRequest: PRE_EXISTING_LETTER_REQUEST }
     });
     clickButtonAndExpectChoice(pal, /mail this myself/i, LetterRequestMailChoice.USER_WILL_MAIL);
@@ -39,7 +39,7 @@ describe('landlord details page', () => {
 
   it('works when user wants us to mail the letter', async () => {
     const pal = new AppTesterPal(<LetterOfComplaintRoutes />, {
-      url: Routes.loc.preview,
+      url: Routes.locale.loc.preview,
       session: { letterRequest: PRE_EXISTING_LETTER_REQUEST }
     });
     pal.clickButtonOrLink(/looks good to me/i);
diff --git a/frontend/lib/tests/pages/loc-confirmation.test.tsx b/frontend/lib/tests/pages/loc-confirmation.test.tsx
index 1e2f9d46e..6637c5596 100644
--- a/frontend/lib/tests/pages/loc-confirmation.test.tsx
+++ b/frontend/lib/tests/pages/loc-confirmation.test.tsx
@@ -10,7 +10,7 @@ describe('letter of complaint confirmation', () => {
 
   const createPal = (mailChoice: LetterRequestMailChoice) =>
     new AppTesterPal(<LetterOfComplaintRoutes/>, {
-      url: Routes.loc.confirmation,
+      url: Routes.locale.loc.confirmation,
       session: {
         letterRequest: {
           updatedAt: "2018-09-14T01:42:12.829983+00:00",
diff --git a/frontend/lib/tests/pages/onboarding-step-1.test.tsx b/frontend/lib/tests/pages/onboarding-step-1.test.tsx
index cf493ba0c..3a52b6f58 100644
--- a/frontend/lib/tests/pages/onboarding-step-1.test.tsx
+++ b/frontend/lib/tests/pages/onboarding-step-1.test.tsx
@@ -8,7 +8,7 @@ import { FakeGeoResults } from '../util';
 import Routes from '../../routes';
 
 const PROPS = {
-  routes: Routes.onboarding,
+  routes: Routes.locale.onboarding,
   toCancel: '/cancel'
 };
 
diff --git a/frontend/lib/tests/pages/onboarding-step-2.test.tsx b/frontend/lib/tests/pages/onboarding-step-2.test.tsx
index 9a6b80d14..42cc3b8ae 100644
--- a/frontend/lib/tests/pages/onboarding-step-2.test.tsx
+++ b/frontend/lib/tests/pages/onboarding-step-2.test.tsx
@@ -9,7 +9,7 @@ describe('onboarding step 2 page', () => {
   afterEach(AppTesterPal.cleanup);
 
   it('opens eviction modal', () => {
-    const pal = new AppTesterPal(<OnboardingStep2 routes={Routes.onboarding} />);
+    const pal = new AppTesterPal(<OnboardingStep2 routes={Routes.locale.onboarding} />);
     const getDialog = () => pal.getDialogWithLabel(/You need legal help/i);
 
     // When we enable the checkbox, the dialog should show.
diff --git a/frontend/lib/tests/pages/onboarding-step-3.test.tsx b/frontend/lib/tests/pages/onboarding-step-3.test.tsx
index ad6d8d8b7..e297aaae0 100644
--- a/frontend/lib/tests/pages/onboarding-step-3.test.tsx
+++ b/frontend/lib/tests/pages/onboarding-step-3.test.tsx
@@ -9,7 +9,7 @@ import { getLeaseChoiceLabels } from '../../../../common-data/lease-choices';
 
 
 const PROPS = {
-  routes: Routes.onboarding
+  routes: Routes.locale.onboarding
 };
 
 const STEP_3 = new OnboardingStep3(PROPS);
diff --git a/frontend/lib/tests/pages/onboarding-step-4.test.tsx b/frontend/lib/tests/pages/onboarding-step-4.test.tsx
index bfa82b612..9b1070373 100644
--- a/frontend/lib/tests/pages/onboarding-step-4.test.tsx
+++ b/frontend/lib/tests/pages/onboarding-step-4.test.tsx
@@ -7,7 +7,7 @@ import Routes from '../../routes';
 import { OnboardingInfoSignupIntent } from '../../queries/globalTypes';
 
 const PROPS = {
-  routes: Routes.onboarding,
+  routes: Routes.locale.onboarding,
   toSuccess: '/success',
   signupIntent: OnboardingInfoSignupIntent.HP
 };
diff --git a/frontend/lib/tests/progress-routes.test.tsx b/frontend/lib/tests/progress-routes.test.tsx
index d448617cd..299fb7877 100644
--- a/frontend/lib/tests/progress-routes.test.tsx
+++ b/frontend/lib/tests/progress-routes.test.tsx
@@ -13,7 +13,7 @@ const myRoutesProps: ProgressRoutesProps = {
   confirmationSteps: []
 };
 
-const MyRoutes = buildProgressRoutesComponent(myRoutesProps);
+const MyRoutes = buildProgressRoutesComponent(() => myRoutesProps);
 
 describe("ProgressRoutes", () => {
   afterEach(AppTesterPal.cleanup);
diff --git a/frontend/lib/tests/routes.test.ts b/frontend/lib/tests/routes.test.ts
index 5c577077e..f2c5b9650 100644
--- a/frontend/lib/tests/routes.test.ts
+++ b/frontend/lib/tests/routes.test.ts
@@ -1,5 +1,14 @@
-import { isModalRoute, RouteMap, getSignupIntentOnboardingInfo } from "../routes";
+import Routes, { isModalRoute, RouteMap, getSignupIntentOnboardingInfo } from "../routes";
 import { OnboardingInfoSignupIntent } from "../queries/globalTypes";
+import i18n from "../i18n";
+
+test('Routes object responds to locale changes', () => {
+  expect(Routes.locale.home).toBe('/');
+  i18n.initialize('en');
+  expect(Routes.locale.home).toBe('/en/');
+  i18n.initialize('');
+  expect(Routes.locale.home).toBe('/');
+});
 
 test('isModalRoute() works', () => {
   expect(isModalRoute('/blah')).toBe(false);
diff --git a/frontend/lib/tests/setup.ts b/frontend/lib/tests/setup.ts
index 782cae417..98c27b5ea 100644
--- a/frontend/lib/tests/setup.ts
+++ b/frontend/lib/tests/setup.ts
@@ -5,9 +5,12 @@ import { defaultContext } from '../app-context';
 import { FakeAppContext } from './util';
 import chalk from 'chalk';
 import './confetti.setup';
+import i18n from '../i18n';
 
 configure({ adapter: new Adapter() });
 
+i18n.initialize('');
+
 Object.keys(FakeAppContext).forEach(prop => {
   Object.defineProperty(defaultContext, prop, {
     value: (FakeAppContext as any)[prop]
diff --git a/hpaction/tests/test_models.py b/hpaction/tests/test_models.py
index e387b92ba..e33e50d50 100644
--- a/hpaction/tests/test_models.py
+++ b/hpaction/tests/test_models.py
@@ -2,6 +2,7 @@
 from freezegun import freeze_time
 
 from users.tests.factories import UserFactory
+from project.tests.util import strip_locale
 from .factories import HPActionDocumentsFactory, UploadTokenFactory
 from ..models import (
     HPActionDocuments, UploadToken, UPLOAD_TOKEN_LIFETIME,
@@ -41,7 +42,8 @@ def test_create_documents_from_works(self, db, django_file_storage):
 
     def test_get_upload_url_works(self, db):
         token = UploadToken(id='boop')
-        assert token.get_upload_url() == 'https://example.com/hp/upload/boop'
+        url = strip_locale(token.get_upload_url())
+        assert url == 'https://example.com/hp/upload/boop'
 
 
 class TestHPActionDocuments:
diff --git a/loc/tests/test_admin.py b/loc/tests/test_admin.py
index 1e9e9d4d9..32313cdf4 100644
--- a/loc/tests/test_admin.py
+++ b/loc/tests/test_admin.py
@@ -2,6 +2,7 @@
 
 from users.models import JustfixUser
 from users.tests.factories import UserFactory
+from project.tests.util import strip_locale
 from loc.admin import LetterRequestInline, print_loc_envelopes
 from loc.models import LetterRequest
 
@@ -25,4 +26,5 @@ def test_loc_actions_shows_pdf_link_when_user_has_letter_request():
 def test_print_loc_envelopes_works():
     user = UserFactory()
     redirect = print_loc_envelopes(None, None, JustfixUser.objects.all())
-    assert redirect.url == f'/loc/admin/envelopes.pdf?user_ids={user.pk}'
+    url = strip_locale(redirect.url)
+    assert url == f'/loc/admin/envelopes.pdf?user_ids={user.pk}'
diff --git a/loc/tests/test_views.py b/loc/tests/test_views.py
index b78cd8e48..89333d3f7 100644
--- a/loc/tests/test_views.py
+++ b/loc/tests/test_views.py
@@ -1,4 +1,5 @@
 from functools import wraps
+from django.urls import reverse
 import pytest
 
 from users.tests.factories import UserFactory
@@ -22,6 +23,18 @@
     "ignore:The html argument of XMLParser")
 
 
+def example_url(format: str) -> str:
+    return reverse('loc_example', args=(format,))
+
+
+def letter_url(format: str) -> str:
+    return reverse('loc', args=(format,))
+
+
+def admin_letter_url(user_id: int) -> str:
+    return reverse('loc_for_user', kwargs={'user_id': user_id})
+
+
 def requires_pdf_rendering(fn):
     @pytest.mark.skipif(not can_we_render_pdfs(),
                         reason='PDF generation is unsupported')
@@ -59,12 +72,12 @@ def test_render_document_raises_err_on_invalid_format():
 
 
 def test_letter_requires_login(client):
-    res = client.get('/loc/letter.html')
+    res = client.get(letter_url('html'))
     assert res.status_code == 302
 
 
 def get_letter_html(client):
-    res = client.get('/loc/letter.html')
+    res = client.get(letter_url('html'))
     assert res.status_code == 200
     assert res['Content-Type'] == 'text/html; charset=utf-8'
     return res.content.decode('utf-8')
@@ -100,21 +113,21 @@ def test_letter_html_includes_expected_content(client):
 
 
 def test_example_html_works(client):
-    res = client.get('/loc/example.html')
+    res = client.get(example_url('html'))
     assert res.status_code == 200
     assert res['Content-Type'] == 'text/html; charset=utf-8'
 
 
 @requires_pdf_rendering
 def test_letter_pdf_works(admin_client):
-    res = admin_client.get('/loc/letter.pdf')
+    res = admin_client.get(letter_url('pdf'))
     assert res.status_code == 200
     assert res['Content-Type'] == 'application/pdf'
 
 
 @requires_pdf_rendering
 def test_example_pdf_works(client):
-    res = client.get('/loc/example.pdf')
+    res = client.get(example_url('pdf'))
     assert res.status_code == 200
     assert res['Content-Type'] == 'application/pdf'
 
@@ -122,13 +135,13 @@ def test_example_pdf_works(client):
 @requires_pdf_rendering
 def test_admin_letter_pdf_works(outreach_client):
     user = UserFactory()
-    res = outreach_client.get(f'/loc/admin/{user.pk}/letter.pdf')
+    res = outreach_client.get(admin_letter_url(user.pk))
     assert res.status_code == 200
     assert res['Content-Type'] == 'application/pdf'
 
 
 def test_admin_letter_pdf_returns_404_for_nonexistent_users(admin_client):
-    res = admin_client.get(f'/loc/admin/1024/letter.pdf')
+    res = admin_client.get(admin_letter_url(1024))
     assert res.status_code == 404
 
 
@@ -138,10 +151,11 @@ def test_admin_letter_pdf_is_inaccessible_to_non_staff_users(client):
     client.force_login(user)
 
     # Yes, even the user's own LoC should be forbidden to them.
-    res = client.get(f'/loc/admin/{user.pk}/letter.pdf')
+    url = admin_letter_url(user.pk)
+    res = client.get(url)
 
     assert res.status_code == 302
-    assert res.url == f"/login?next=/loc/admin/{user.pk}/letter.pdf"
+    assert res.url == f"/login?next={url}"
 
 
 @pytest.mark.django_db
@@ -149,17 +163,17 @@ def test_admin_envelopes_pdf_is_inaccessible_to_non_staff_users(client):
     user = UserFactory()
     client.force_login(user)
 
-    res = client.get(f'/loc/admin/envelopes.pdf')
+    res = client.get(reverse('loc_envelopes'))
 
     assert res.status_code == 302
-    assert res.url == f"/login?next=/loc/admin/envelopes.pdf"
+    assert res.url == f"/login?next={reverse('loc_envelopes')}"
 
 
 @requires_pdf_rendering
 def test_admin_envelopes_pdf_works(outreach_client):
     user = create_user_with_all_info()
     bare_user = UserFactory(phone_number='6141234567', username='blah')
-    res = outreach_client.get(f'/loc/admin/envelopes.pdf?user_ids={user.pk},{bare_user.pk},zz')
+    res = outreach_client.get(f'{reverse("loc_envelopes")}?user_ids={user.pk},{bare_user.pk},zz')
     assert res.status_code == 200
     assert res['Content-Type'] == 'application/pdf'
     assert res.context['users'] == [user]
diff --git a/loc/urls.py b/loc/urls.py
index 0c28f0f91..28bb965f7 100644
--- a/loc/urls.py
+++ b/loc/urls.py
@@ -8,5 +8,5 @@
     path(r'admin/envelopes.pdf', views.envelopes, name='loc_envelopes'),
     path(r'admin/<int:user_id>/letter.pdf', views.letter_of_complaint_pdf_for_user,
          name='loc_for_user'),
-    re_path(r'^example\.(html|pdf)$', views.example_doc),
+    re_path(r'^example\.(html|pdf)$', views.example_doc, name='loc_example'),
 ]
diff --git a/loc/views.py b/loc/views.py
index 387d997cb..79a027b62 100644
--- a/loc/views.py
+++ b/loc/views.py
@@ -6,6 +6,7 @@
 from django.contrib.auth.decorators import login_required, permission_required
 from django.template.loader import render_to_string
 from django.shortcuts import get_object_or_404
+from django.utils import translation
 
 from twofactor.decorators import twofactor_required
 from users.models import JustfixUser, VIEW_LETTER_REQUEST_PERMISSION
@@ -155,6 +156,14 @@ def render_document(request, template_name: str, context: Dict[str, Any], format
     if format not in ['html', 'pdf']:
         raise ValueError(f'unknown format "{format}"')
 
+    # For now, we always want to localize the letter of complaint in English.
+    # Even if we don't translate the letter itself to other languages, some
+    # templating functionality provided by Django (such as date formatting) will
+    # take the current locale into account, and we don't want e.g. a letter to
+    # have English paragraphs but Spanish dates. So we'll explicitly set
+    # the locale here.
+    translation.activate('en')
+
     if format == 'html':
         html = render_to_string(template_name, context={
             **context,
diff --git a/project/justfix_environment.py b/project/justfix_environment.py
index df2f68b2b..ff73f1bcc 100644
--- a/project/justfix_environment.py
+++ b/project/justfix_environment.py
@@ -166,6 +166,9 @@ class JustfixEnvironment(typed_environ.BaseEnvironment):
     # not provided, mapbox integration will be disabled.
     MAPBOX_ACCESS_TOKEN: str = ''
 
+    # Whether or not to enable internationalization/localization.
+    ENABLE_I18N: bool = False
+
 
 class JustfixDevelopmentDefaults(JustfixEnvironment):
     '''
diff --git a/project/settings.py b/project/settings.py
index fa9cce5f0..b328a8bb1 100644
--- a/project/settings.py
+++ b/project/settings.py
@@ -72,6 +72,7 @@
     'django.middleware.security.SecurityMiddleware',
     'whitenoise.middleware.WhiteNoiseMiddleware',
     'django.contrib.sessions.middleware.SessionMiddleware',
+    'django.middleware.locale.LocaleMiddleware',
     'django.middleware.common.CommonMiddleware',
     'django.middleware.csrf.CsrfViewMiddleware',
     'django.contrib.auth.middleware.AuthenticationMiddleware',
@@ -177,13 +178,17 @@
 # Internationalization
 # https://docs.djangoproject.com/en/2.1/topics/i18n/
 
-LANGUAGE_CODE = 'en-us'
+LANGUAGE_CODE = 'en'
+
+LANGUAGES = [
+    ('en', 'English'),
+]
 
 TIME_ZONE = 'UTC'
 
-USE_I18N = True
+USE_I18N = env.ENABLE_I18N
 
-USE_L10N = True
+USE_L10N = env.ENABLE_I18N
 
 USE_TZ = True
 
diff --git a/project/tests/test_site_util.py b/project/tests/test_site_util.py
index bb4dc969f..5c7bc7562 100644
--- a/project/tests/test_site_util.py
+++ b/project/tests/test_site_util.py
@@ -1,4 +1,5 @@
 from django.test import override_settings, TestCase
+from django.conf import settings
 
 from ..util.site_util import absolute_reverse, absolutify_url
 
@@ -6,9 +7,13 @@
 class SiteUtilsTests(TestCase):
     @override_settings(DEBUG=False)
     def test_absolute_reverse_works(self):
+        if settings.USE_I18N:
+            url = 'https://example.com/en/graphql'
+        else:
+            url = 'https://example.com/graphql'
         self.assertEqual(
             absolute_reverse('batch-graphql'),
-            'https://example.com/graphql'
+            url
         )
 
     def test_absolutify_url_raises_error_on_non_absolute_paths(self):
diff --git a/project/tests/test_views.py b/project/tests/test_views.py
index e9bbee2c1..1f412c522 100644
--- a/project/tests/test_views.py
+++ b/project/tests/test_views.py
@@ -15,6 +15,13 @@
 from frontend.tests import test_safe_mode
 
 
+def react_url(path: str) -> str:
+    base_url = reverse('react')
+    if base_url.endswith('/'):
+        base_url = base_url[:-1]
+    return f"{base_url}{path}"
+
+
 def test_get_legacy_form_submission_raises_errors(graphql_client):
     request = graphql_client.request
     with pytest.raises(LegacyFormSubmissionError, match='No GraphQL query found'):
@@ -45,7 +52,7 @@ def test_get_initial_session_works(graphql_client):
 
 
 def test_invalid_post_returns_400(client):
-    response = client.post('/')
+    response = client.post(react_url('/'))
     assert response.status_code == 400
     assert response.content == b'No GraphQL query found'
 
@@ -56,7 +63,7 @@ def test_invalid_post_returns_400(client):
 
 
 def test_index_works_when_not_in_safe_mode(client):
-    response = client.get('/')
+    response = client.get(react_url('/'))
     assert response.status_code == 200
     assert 'JustFix.nyc' in response.context['title_tag']
     assert '<nav' in response.context['initial_render']
@@ -70,7 +77,7 @@ def test_index_works_when_not_in_safe_mode(client):
 @pytest.mark.django_db
 def test_index_works_when_in_safe_mode(client):
     test_safe_mode.enable_safe_mode(client)
-    response = client.get('/')
+    response = client.get(react_url('/'))
     assert response.status_code == 200
 
     html = response.content.decode('utf-8')
@@ -79,10 +86,18 @@ def test_index_works_when_in_safe_mode(client):
     test_safe_mode.assert_html_is_in_safe_mode(html)
 
 
+def test_redirects_to_locale_work(client, settings):
+    if not settings.USE_I18N:
+        pytest.skip('Internationalization is disabled')
+    response = client.get('/')
+    assert response.status_code == 302
+    assert response['location'] == '/en/'
+
+
 def test_pages_with_redirects_work(client):
     response = client.get('/dev/examples/redirect')
     assert response.status_code == 302
-    assert response['location'] == '/'
+    assert response['location'] == react_url('/')
 
 
 def test_pages_with_extra_bundles_work(client):
@@ -130,13 +145,13 @@ def test_admin_login_is_ours(client):
 
 
 def test_404_works(client):
-    response = client.get('/nonexistent')
+    response = client.get(react_url('/nonexistent'))
     assert response.status_code == 404
 
 
 @patch('project.views.TEST_INTERNAL_SERVER_ERROR', True)
 def test_500_works(client):
-    response = client.get('/')
+    response = client.get(react_url('/'))
     assert response.status_code == 500
     assert response.context['bundle_urls'] == []
 
@@ -171,7 +186,7 @@ def test_form_submission_redirects_on_success(django_app):
     form['exampleField'] = 'hi'
     response = form.submit()
     assert response.status == '302 Found'
-    assert response['Location'] == '/'
+    assert response['Location'] == react_url('/')
 
 
 def test_form_submission_shows_errors(django_app):
@@ -245,7 +260,7 @@ def test_form_submission_preserves_boolean_fields(django_app):
 @pytest.mark.django_db
 def test_successful_login_redirects_to_next(django_app):
     UserFactory(phone_number='5551234567', password='test123')
-    form = django_app.get('/login?next=/boop').forms[0]
+    form = django_app.get(react_url('/login') + '?next=/boop').forms[0]
 
     form['phoneNumber'] = '5551234567'
     form['password'] = 'test123'
@@ -257,7 +272,7 @@ def test_successful_login_redirects_to_next(django_app):
 
 @pytest.mark.django_db
 def test_unsuccessful_login_shows_error(django_app):
-    form = django_app.get('/login?next=/boop').forms[0]
+    form = django_app.get(react_url('/login') + '?next=/boop').forms[0]
 
     form['phoneNumber'] = '5551234567'
     form['password'] = 'test123'
diff --git a/project/tests/util.py b/project/tests/util.py
index 137d352af..0a78adbe1 100644
--- a/project/tests/util.py
+++ b/project/tests/util.py
@@ -1,6 +1,7 @@
 from unittest.mock import patch
 from functools import wraps
 from django.http import QueryDict
+from django.conf import settings
 
 from project.views import FRONTEND_QUERY_DIR
 
@@ -42,3 +43,24 @@ def wrapper(*fn_args, **fn_kwargs):
         return wrapper
 
     return decorator
+
+
+def strip_locale(url: str) -> str:
+    '''
+    If the given URL has a locale prefix in its
+    pathname, remove it. For example:
+
+        >>> strip_locale('https://blah/blarg')
+        'https://blah/blarg'
+
+        >>> strip_locale('https://blah/en/blarg')
+        'https://blah/blarg'
+    '''
+
+    # This isn't particularly precise, but it gets
+    # the job done for testing, which is all we're
+    # using it for.
+    for lang, _ in settings.LANGUAGES:
+        url = url.replace(f"/{lang}/", "/")
+
+    return url
diff --git a/project/urls.py b/project/urls.py
index 874a7991e..5e9ac80ee 100644
--- a/project/urls.py
+++ b/project/urls.py
@@ -16,6 +16,7 @@
 from django.contrib import admin
 from django.urls import path, re_path, include
 from django.conf import settings
+from django.conf.urls.i18n import i18n_patterns
 from graphene_django.views import GraphQLView
 
 from legacy_tenants.views import redirect_to_legacy_app
@@ -26,18 +27,20 @@
 admin.site.site_title = "Tenant App admin"
 admin.site.index_title = "Justfix.nyc Tenant App administration"
 
+dev_patterns = ([
+    path('examples/server-error/<slug:id>', example_server_error),
+    re_path(r'^.*$', react_rendered_view),
+], 'dev')
+
 urlpatterns = [
     path('verify', twofactor.views.verify, name='verify'),
     path('health', health),
-    path('admin/login/', react_rendered_view, kwargs={'url': 'admin/login/'}),
+    path('admin/login/', react_rendered_view),
     path('admin/', admin.site.urls),
-    path('loc/', include('loc.urls')),
-    path('hp/', include('hpaction.urls')),
     path('safe-mode/', include('frontend.safe_mode')),
     path('legacy-app', redirect_to_legacy_app, name='redirect-to-legacy-app'),
     path('favicon.ico', redirect_favicon),
-    path('dev/examples/server-error/<slug:id>', example_server_error),
-    path('graphql', GraphQLView.as_view(batch=True), name='batch-graphql'),
+    path('dev/', include(dev_patterns, namespace='dev')),
 ]
 
 if settings.DEBUG:
@@ -47,4 +50,9 @@
     urlpatterns.append(
         path('graphiql', GraphQLView.as_view(graphiql=True)))
 
-urlpatterns.append(re_path(r'^(?P<url>.*)$', react_rendered_view))
+urlpatterns += i18n_patterns(
+    path('loc/', include('loc.urls')),
+    path('hp/', include('hpaction.urls')),
+    path('graphql', GraphQLView.as_view(batch=True), name='batch-graphql'),
+    re_path(r'.*$', react_rendered_view, name='react'),
+)
diff --git a/project/views.py b/project/views.py
index 1e21e4e0b..fcf803075 100644
--- a/project/views.py
+++ b/project/views.py
@@ -5,6 +5,7 @@
 from django.views.decorators.http import require_POST
 from django.views.decorators.csrf import csrf_exempt
 from django.utils.safestring import SafeString
+from django.utils import translation
 from django.shortcuts import render, redirect
 from django.urls import reverse
 from django.conf import settings
@@ -137,8 +138,11 @@ def get_legacy_form_submission(request):
     }
 
 
-def react_rendered_view(request, url: str):
-    url = f'/{url}'
+def react_rendered_view(request):
+    url = request.path
+    cur_language = ''
+    if settings.USE_I18N:
+        cur_language = translation.get_language_from_request(request, check_path=True)
     querystring = request.GET.urlencode()
     if querystring:
         url += f'?{querystring}'
@@ -150,6 +154,7 @@ def react_rendered_view(request, url: str):
     initial_props = {
         'initialURL': url,
         'initialSession': get_initial_session(request),
+        'locale': cur_language,
         'server': {
             'originURL': request.build_absolute_uri('/')[:-1],
             'staticURL': settings.STATIC_URL,