diff --git a/src/activities-app/App.vue b/src/activities-app/App.vue
index 4aaa827..bc520ae 100644
--- a/src/activities-app/App.vue
+++ b/src/activities-app/App.vue
@@ -1,6 +1,7 @@
 <script setup lang="ts">
 import { computed, ref } from 'vue'
 import { useRoute, useRouter } from 'vue-router'
+import { useI18n } from 'vue-i18n'
 import { Toaster } from '@/components/ui/sonner'
 import LoginDialog from '@/components/auth/LoginDialog.vue'
 import { useTheme } from '@/components/theme-provider'
@@ -11,19 +12,20 @@ import {
 
 const route = useRoute()
 const router = useRouter()
+const { t } = useI18n()
 
 useTheme()
 
 const showLoginDialog = ref(false)
 
 // Bottom navigation tabs (p'a semana style)
-const bottomTabs = [
-  { name: 'Feed', icon: Search, path: '/activities' },
-  { name: 'Calendar', icon: CalendarDays, path: '/activities/calendar' },
-  { name: 'Map', icon: Map, path: '/activities/map' },
-  { name: 'Favorites', icon: Heart, path: '/activities/favorites' },
-  { name: 'Settings', icon: Settings, path: '/settings' },
-]
+const bottomTabs = computed(() => [
+  { name: t('activities.nav.feed'), icon: Search, path: '/activities' },
+  { name: t('activities.nav.calendar'), icon: CalendarDays, path: '/activities/calendar' },
+  { name: t('activities.nav.map'), icon: Map, path: '/activities/map' },
+  { name: t('activities.nav.favorites'), icon: Heart, path: '/activities/favorites' },
+  { name: t('activities.nav.settings'), icon: Settings, path: '/settings' },
+])
 
 const isLoginPage = computed(() => route.path === '/login')
 
diff --git a/src/activities-app/views/SettingsPage.vue b/src/activities-app/views/SettingsPage.vue
index 2a4ad83..be6b437 100644
--- a/src/activities-app/views/SettingsPage.vue
+++ b/src/activities-app/views/SettingsPage.vue
@@ -9,7 +9,7 @@ import { useI18n } from 'vue-i18n'
 import { Sun, Moon, LogIn, LogOut } from 'lucide-vue-next'
 
 const { theme, setTheme } = useTheme()
-const { locale } = useI18n()
+const { t, locale } = useI18n()
 
 const languages: { code: AvailableLocale; label: string }[] = [
   { code: 'fr', label: 'Français' },
@@ -35,27 +35,27 @@ async function handleLogout() {
 
 <template>
   <div class="container mx-auto px-4 py-6 max-w-lg">
-    <h1 class="text-2xl font-bold text-foreground mb-6">Settings</h1>
+    <h1 class="text-2xl font-bold text-foreground mb-6">{{ t('activities.settings.title') }}</h1>
 
     <!-- Account -->
     <div class="space-y-4">
-      <h2 class="text-sm font-medium text-muted-foreground uppercase tracking-wide">Account</h2>
+      <h2 class="text-sm font-medium text-muted-foreground uppercase tracking-wide">{{ t('activities.settings.account') }}</h2>
       <div v-if="isAuthenticated" class="bg-muted/50 rounded-lg p-4 space-y-3">
         <p class="text-sm text-foreground font-mono truncate">
           {{ userPubkey }}
         </p>
         <Button variant="outline" size="sm" class="w-full gap-2" @click="handleLogout">
           <LogOut class="w-4 h-4" />
-          Log out
+          {{ t('activities.settings.logOut') }}
         </Button>
       </div>
       <div v-else class="bg-muted/50 rounded-lg p-4">
         <p class="text-sm text-muted-foreground mb-3">
-          Log in to bookmark activities, RSVP, and purchase tickets.
+          {{ t('activities.settings.loginPrompt') }}
         </p>
         <Button size="sm" class="w-full gap-2" @click="$router.push('/login')">
           <LogIn class="w-4 h-4" />
-          Log in
+          {{ t('activities.settings.logIn') }}
         </Button>
       </div>
     </div>
@@ -64,9 +64,9 @@ async function handleLogout() {
 
     <!-- Appearance -->
     <div class="space-y-4">
-      <h2 class="text-sm font-medium text-muted-foreground uppercase tracking-wide">Appearance</h2>
+      <h2 class="text-sm font-medium text-muted-foreground uppercase tracking-wide">{{ t('activities.settings.appearance') }}</h2>
       <div class="flex items-center justify-between bg-muted/50 rounded-lg p-4">
-        <span class="text-sm text-foreground">Theme</span>
+        <span class="text-sm text-foreground">{{ t('activities.settings.theme') }}</span>
         <Button variant="outline" size="icon" class="h-8 w-8" @click="toggleTheme">
           <Sun v-if="theme === 'dark'" class="w-4 h-4" />
           <Moon v-else class="w-4 h-4" />
@@ -78,7 +78,7 @@ async function handleLogout() {
 
     <!-- Language -->
     <div class="space-y-4">
-      <h2 class="text-sm font-medium text-muted-foreground uppercase tracking-wide">Language</h2>
+      <h2 class="text-sm font-medium text-muted-foreground uppercase tracking-wide">{{ t('activities.settings.language') }}</h2>
       <div class="flex gap-2">
         <Button
           v-for="lang in languages"
diff --git a/src/i18n/locales/en.ts b/src/i18n/locales/en.ts
index 70fe924..fd9b1a5 100644
--- a/src/i18n/locales/en.ts
+++ b/src/i18n/locales/en.ts
@@ -90,6 +90,34 @@ const messages: LocaleMessages = {
       pending: 'Pending',
       registered: 'Registered',
     },
+    nav: {
+      feed: 'Feed',
+      calendar: 'Calendar',
+      map: 'Map',
+      favorites: 'Favorites',
+      settings: 'Settings',
+    },
+    search: {
+      placeholder: 'Search activities...',
+      noResults: 'No activities found',
+    },
+    favorites: {
+      title: 'Favorites',
+      loginPrompt: 'Log in to save your favorite activities',
+      empty: 'No favorites yet',
+      emptyHint: 'Tap the heart icon on any activity to save it here',
+      logIn: 'Log in',
+    },
+    settings: {
+      title: 'Settings',
+      account: 'Account',
+      loginPrompt: 'Log in to bookmark activities, RSVP, and purchase tickets.',
+      logIn: 'Log in',
+      logOut: 'Log out',
+      appearance: 'Appearance',
+      theme: 'Theme',
+      language: 'Language',
+    },
   },
   dateTimeFormats: {
     short: {
diff --git a/src/i18n/locales/es.ts b/src/i18n/locales/es.ts
index 4899153..f707db0 100644
--- a/src/i18n/locales/es.ts
+++ b/src/i18n/locales/es.ts
@@ -90,6 +90,34 @@ const messages: LocaleMessages = {
       pending: 'Pendiente',
       registered: 'Registrado',
     },
+    nav: {
+      feed: 'Inicio',
+      calendar: 'Calendario',
+      map: 'Mapa',
+      favorites: 'Favoritos',
+      settings: 'Ajustes',
+    },
+    search: {
+      placeholder: 'Buscar actividades...',
+      noResults: 'No se encontraron actividades',
+    },
+    favorites: {
+      title: 'Favoritos',
+      loginPrompt: 'Inicia sesión para guardar tus actividades favoritas',
+      empty: 'Aún no tienes favoritos',
+      emptyHint: 'Toca el corazón en cualquier actividad para guardarla aquí',
+      logIn: 'Iniciar sesión',
+    },
+    settings: {
+      title: 'Ajustes',
+      account: 'Cuenta',
+      loginPrompt: 'Inicia sesión para guardar actividades, confirmar asistencia y comprar boletos.',
+      logIn: 'Iniciar sesión',
+      logOut: 'Cerrar sesión',
+      appearance: 'Apariencia',
+      theme: 'Tema',
+      language: 'Idioma',
+    },
   },
   dateTimeFormats: {
     short: {
diff --git a/src/i18n/locales/fr.ts b/src/i18n/locales/fr.ts
index e18f854..bd012eb 100644
--- a/src/i18n/locales/fr.ts
+++ b/src/i18n/locales/fr.ts
@@ -90,6 +90,34 @@ const messages: LocaleMessages = {
       pending: 'En attente',
       registered: 'Enregistré',
     },
+    nav: {
+      feed: 'Fil',
+      calendar: 'Calendrier',
+      map: 'Carte',
+      favorites: 'Favoris',
+      settings: 'Réglages',
+    },
+    search: {
+      placeholder: 'Rechercher des activités...',
+      noResults: 'Aucune activité trouvée',
+    },
+    favorites: {
+      title: 'Favoris',
+      loginPrompt: 'Connectez-vous pour sauvegarder vos activités préférées',
+      empty: 'Pas encore de favoris',
+      emptyHint: "Appuyez sur le cœur d'une activité pour la sauvegarder ici",
+      logIn: 'Se connecter',
+    },
+    settings: {
+      title: 'Réglages',
+      account: 'Compte',
+      loginPrompt: 'Connectez-vous pour sauvegarder des activités, confirmer votre présence et acheter des billets.',
+      logIn: 'Se connecter',
+      logOut: 'Se déconnecter',
+      appearance: 'Apparence',
+      theme: 'Thème',
+      language: 'Langue',
+    },
   },
   dateTimeFormats: {
     short: {
diff --git a/src/i18n/types.ts b/src/i18n/types.ts
index 9faf7d7..cb303a0 100644
--- a/src/i18n/types.ts
+++ b/src/i18n/types.ts
@@ -65,6 +65,34 @@ export interface LocaleMessages {
       pending: string
       registered: string
     }
+    nav: {
+      feed: string
+      calendar: string
+      map: string
+      favorites: string
+      settings: string
+    }
+    search: {
+      placeholder: string
+      noResults: string
+    }
+    favorites: {
+      title: string
+      loginPrompt: string
+      empty: string
+      emptyHint: string
+      logIn: string
+    }
+    settings: {
+      title: string
+      account: string
+      loginPrompt: string
+      logIn: string
+      logOut: string
+      appearance: string
+      theme: string
+      language: string
+    }
   }
   // Add date/time formats
   dateTimeFormats: {
diff --git a/src/modules/activities/components/ActivityCalendarView.vue b/src/modules/activities/components/ActivityCalendarView.vue
index fac8096..e9066d6 100644
--- a/src/modules/activities/components/ActivityCalendarView.vue
+++ b/src/modules/activities/components/ActivityCalendarView.vue
@@ -7,6 +7,7 @@ import {
 } from 'date-fns'
 import { Button } from '@/components/ui/button'
 import { ChevronLeft, ChevronRight } from 'lucide-vue-next'
+import { useDateLocale } from '../composables/useDateLocale'
 import type { Activity } from '../types/activity'
 
 const props = defineProps<{
@@ -18,11 +19,24 @@ const emit = defineEmits<{
   selectActivity: [activity: Activity]
 }>()
 
+const { dateLocale } = useDateLocale()
+
 const currentMonth = ref(new Date())
 
-const monthLabel = computed(() => format(currentMonth.value, 'MMMM yyyy'))
+const monthLabel = computed(() => format(currentMonth.value, 'MMMM yyyy', { locale: dateLocale.value }))
 
-const weekDays = ['M', 'T', 'W', 'T', 'F', 'S', 'S']
+const weekDays = computed(() => {
+  // Generate localized single-letter day names starting from Monday
+  const days: string[] = []
+  // Start from a known Monday (2024-01-01 is a Monday)
+  const monday = new Date(2024, 0, 1)
+  for (let i = 0; i < 7; i++) {
+    const d = new Date(monday)
+    d.setDate(d.getDate() + i)
+    days.push(format(d, 'EEEEE', { locale: dateLocale.value }))
+  }
+  return days
+})
 
 const calendarDays = computed(() => {
   const monthStart = startOfMonth(currentMonth.value)
@@ -134,7 +148,7 @@ function nextMonth() {
     <!-- Selected day activities -->
     <div v-if="selectedDay" class="border-t pt-4 space-y-2">
       <h3 class="text-sm font-medium text-muted-foreground">
-        {{ format(selectedDay, 'EEEE, MMMM d') }}
+        {{ format(selectedDay, 'EEEE, MMMM d', { locale: dateLocale }) }}
         <span v-if="selectedDayActivities.length > 0" class="ml-1">
           ({{ selectedDayActivities.length }})
         </span>
diff --git a/src/modules/activities/components/ActivityCard.vue b/src/modules/activities/components/ActivityCard.vue
index 62399e6..71054fb 100644
--- a/src/modules/activities/components/ActivityCard.vue
+++ b/src/modules/activities/components/ActivityCard.vue
@@ -6,6 +6,7 @@ import { Card, CardContent } from '@/components/ui/card'
 import { Badge } from '@/components/ui/badge'
 import { MapPin, Calendar, Ticket } from 'lucide-vue-next'
 import BookmarkButton from './BookmarkButton.vue'
+import { useDateLocale } from '../composables/useDateLocale'
 import type { Activity } from '../types/activity'
 
 const props = defineProps<{
@@ -17,16 +18,18 @@ const emit = defineEmits<{
 }>()
 
 const { t } = useI18n()
+const { dateLocale } = useDateLocale()
 
 const dateDisplay = computed(() => {
   const a = props.activity
   if (!a.startDate || isNaN(a.startDate.getTime())) return ''
   try {
+    const opts = { locale: dateLocale.value }
     if (a.type === 'date') {
-      return format(a.startDate, 'EEE, MMM d')
+      return format(a.startDate, 'EEE, MMM d', opts)
     }
-    const date = format(a.startDate, 'EEE, MMM d')
-    const time = format(a.startDate, 'HH:mm')
+    const date = format(a.startDate, 'EEE, MMM d', opts)
+    const time = format(a.startDate, 'HH:mm', opts)
     return `${date} \u2022 ${time}`
   } catch {
     return ''
diff --git a/src/modules/activities/components/ActivityList.vue b/src/modules/activities/components/ActivityList.vue
index 3e31639..726f09e 100644
--- a/src/modules/activities/components/ActivityList.vue
+++ b/src/modules/activities/components/ActivityList.vue
@@ -43,7 +43,7 @@ const { t } = useI18n()
       {{ t('activities.noActivities') }}
     </h3>
     <p class="text-sm text-muted-foreground">
-      Try adjusting your filters or check back later
+      {{ t('activities.search.noResults') }}
     </p>
   </div>
 
diff --git a/src/modules/activities/components/ActivitySearchOverlay.vue b/src/modules/activities/components/ActivitySearchOverlay.vue
index f414dfb..2dd77ab 100644
--- a/src/modules/activities/components/ActivitySearchOverlay.vue
+++ b/src/modules/activities/components/ActivitySearchOverlay.vue
@@ -1,6 +1,8 @@
 <script setup lang="ts">
 import { ref, computed, watch } from 'vue'
+import { useI18n } from 'vue-i18n'
 import { format } from 'date-fns'
+import { useDateLocale } from '../composables/useDateLocale'
 import { Input } from '@/components/ui/input'
 import { Button } from '@/components/ui/button'
 import { Search, X, MapPin, Calendar } from 'lucide-vue-next'
@@ -15,6 +17,8 @@ const emit = defineEmits<{
   select: [activity: Activity]
 }>()
 
+const { t } = useI18n()
+const { dateLocale } = useDateLocale()
 const isOpen = ref(false)
 const inputRef = ref<HTMLInputElement | null>(null)
 
@@ -51,8 +55,9 @@ const showNoResults = computed(() => isOpen.value && isSearching.value && filter
 function formatDate(activity: Activity): string {
   if (!activity.startDate || isNaN(activity.startDate.getTime())) return ''
   try {
-    if (activity.type === 'date') return format(activity.startDate, 'MMM d')
-    return format(activity.startDate, 'MMM d · HH:mm')
+    const opts = { locale: dateLocale.value }
+    if (activity.type === 'date') return format(activity.startDate, 'MMM d', opts)
+    return format(activity.startDate, 'MMM d · HH:mm', opts)
   } catch {
     return ''
   }
@@ -105,7 +110,7 @@ watch(isOpen, (open) => {
         :model-value="searchQuery"
         @update:model-value="handleInput"
         @focus="handleFocus"
-        placeholder="Search activities..."
+        :placeholder="t('activities.search.placeholder')"
         class="pl-9 pr-9"
       />
       <Button
@@ -126,7 +131,7 @@ watch(isOpen, (open) => {
     >
       <!-- No results -->
       <div v-if="showNoResults" class="p-4 text-sm text-muted-foreground text-center">
-        No activities found
+        {{ t('activities.search.noResults') }}
       </div>
 
       <!-- Result items -->
diff --git a/src/modules/activities/components/DatePickerStrip.vue b/src/modules/activities/components/DatePickerStrip.vue
index b692960..f605373 100644
--- a/src/modules/activities/components/DatePickerStrip.vue
+++ b/src/modules/activities/components/DatePickerStrip.vue
@@ -3,6 +3,7 @@ import { ref, computed } from 'vue'
 import { addDays, format, isSameDay, startOfWeek } from 'date-fns'
 import { Button } from '@/components/ui/button'
 import { ChevronLeft, ChevronRight } from 'lucide-vue-next'
+import { useDateLocale } from '../composables/useDateLocale'
 
 const props = defineProps<{
   /** Currently selected date (if any) */
@@ -13,6 +14,8 @@ const emit = defineEmits<{
   select: [date: Date]
 }>()
 
+const { dateLocale } = useDateLocale()
+
 /** Start of the visible week */
 const weekStart = ref(startOfWeek(new Date(), { weekStartsOn: 1 }))
 
@@ -55,7 +58,7 @@ function nextWeek() {
         <span class="text-[10px] font-medium uppercase leading-none"
           :class="isSelected(day) ? 'text-primary-foreground/70' : 'text-muted-foreground'"
         >
-          {{ format(day, 'EEEEE') }}
+          {{ format(day, 'EEEEE', { locale: dateLocale }) }}
         </span>
         <span class="text-sm font-semibold leading-tight mt-0.5">
           {{ format(day, 'd') }}
diff --git a/src/modules/activities/composables/useDateLocale.ts b/src/modules/activities/composables/useDateLocale.ts
new file mode 100644
index 0000000..2b9f805
--- /dev/null
+++ b/src/modules/activities/composables/useDateLocale.ts
@@ -0,0 +1,23 @@
+import { computed } from 'vue'
+import { useI18n } from 'vue-i18n'
+import { fr, es, enUS } from 'date-fns/locale'
+import type { Locale } from 'date-fns'
+
+const localeMap: Record<string, Locale> = {
+  fr,
+  es,
+  en: enUS,
+}
+
+/**
+ * Returns a reactive date-fns Locale based on the current i18n language.
+ */
+export function useDateLocale() {
+  const { locale } = useI18n()
+
+  const dateLocale = computed<Locale>(() => {
+    return localeMap[locale.value] ?? enUS
+  })
+
+  return { dateLocale }
+}
diff --git a/src/modules/activities/views/ActivitiesFavoritesPage.vue b/src/modules/activities/views/ActivitiesFavoritesPage.vue
index 1a474a6..02fd179 100644
--- a/src/modules/activities/views/ActivitiesFavoritesPage.vue
+++ b/src/modules/activities/views/ActivitiesFavoritesPage.vue
@@ -1,6 +1,7 @@
 <script setup lang="ts">
 import { computed, onMounted } from 'vue'
 import { useRouter } from 'vue-router'
+import { useI18n } from 'vue-i18n'
 import { Heart } from 'lucide-vue-next'
 import { Button } from '@/components/ui/button'
 import { toast } from 'vue-sonner'
@@ -11,6 +12,7 @@ import ActivityList from '../components/ActivityList.vue'
 import type { Activity } from '../types/activity'
 
 const router = useRouter()
+const { t } = useI18n()
 const { isAuthenticated } = useAuth()
 const { isBookmarkedByDTag, isLoaded } = useBookmarks()
 const store = useActivitiesStore()
@@ -25,9 +27,9 @@ function handleSelect(activity: Activity) {
 
 onMounted(() => {
   if (!isAuthenticated.value) {
-    toast.info('Log in to save favorites', {
+    toast.info(t('activities.favorites.loginPrompt'), {
       action: {
-        label: 'Log in',
+        label: t('activities.favorites.logIn'),
         onClick: () => router.push('/login'),
       },
     })
@@ -37,14 +39,14 @@ onMounted(() => {
 
 <template>
   <div class="container mx-auto px-4 py-6">
-    <h1 class="text-2xl font-bold text-foreground mb-4">Favorites</h1>
+    <h1 class="text-2xl font-bold text-foreground mb-4">{{ t('activities.favorites.title') }}</h1>
 
     <!-- Not authenticated -->
     <div v-if="!isAuthenticated" class="flex flex-col items-center justify-center py-16 text-center">
-      <Heart class="w-16 h-16 text-muted-foreground/30 mb-4" />
-      <p class="text-muted-foreground mb-3">Log in to save your favorite activities</p>
+      <Heart class="w-16 h-16 text-muted-foreground opacity-30 mb-4" />
+      <p class="text-muted-foreground mb-3">{{ t('activities.favorites.loginPrompt') }}</p>
       <Button variant="outline" size="sm" @click="router.push('/login')">
-        Log in
+        {{ t('activities.favorites.logIn') }}
       </Button>
     </div>
 
@@ -55,9 +57,9 @@ onMounted(() => {
 
     <!-- Empty -->
     <div v-else-if="favoriteActivities.length === 0" class="flex flex-col items-center justify-center py-16 text-center">
-      <Heart class="w-16 h-16 text-muted-foreground/30 mb-4" />
-      <p class="text-muted-foreground">No favorites yet</p>
-      <p class="text-sm text-muted-foreground/70 mt-1">Tap the heart icon on any activity to save it here</p>
+      <Heart class="w-16 h-16 text-muted-foreground opacity-30 mb-4" />
+      <p class="text-muted-foreground">{{ t('activities.favorites.empty') }}</p>
+      <p class="text-sm text-muted-foreground/70 mt-1">{{ t('activities.favorites.emptyHint') }}</p>
     </div>
 
     <!-- Favorites list -->
diff --git a/src/modules/activities/views/ActivityDetailPage.vue b/src/modules/activities/views/ActivityDetailPage.vue
index ef7765a..801e036 100644
--- a/src/modules/activities/views/ActivityDetailPage.vue
+++ b/src/modules/activities/views/ActivityDetailPage.vue
@@ -3,6 +3,7 @@ import { computed } from 'vue'
 import { useRoute, useRouter } from 'vue-router'
 import { useI18n } from 'vue-i18n'
 import { format } from 'date-fns'
+import { useDateLocale } from '../composables/useDateLocale'
 import { Button } from '@/components/ui/button'
 import { Badge } from '@/components/ui/badge'
 import { Separator } from '@/components/ui/separator'
@@ -20,20 +21,22 @@ const { t } = useI18n()
 
 const activityId = route.params.id as string
 const { activity, isLoading, error, reload } = useActivityDetail(activityId)
+const { dateLocale } = useDateLocale()
 
 const dateDisplay = computed(() => {
   if (!activity.value) return ''
   const a = activity.value
+  const opts = { locale: dateLocale.value }
   if (a.type === 'date') {
-    const start = format(a.startDate, 'EEEE, MMMM d, yyyy')
+    const start = format(a.startDate, 'EEEE, MMMM d, yyyy', opts)
     if (a.endDate) {
-      return `${start} — ${format(a.endDate, 'EEEE, MMMM d, yyyy')}`
+      return `${start} — ${format(a.endDate, 'EEEE, MMMM d, yyyy', opts)}`
     }
     return start
   }
-  const start = format(a.startDate, 'EEEE, MMMM d, yyyy \u2022 HH:mm')
+  const start = format(a.startDate, 'EEEE, MMMM d, yyyy \u2022 HH:mm', opts)
   if (a.endDate) {
-    return `${start} — ${format(a.endDate, 'HH:mm')}`
+    return `${start} — ${format(a.endDate, 'HH:mm', opts)}`
   }
   return start
 })