diff --git a/app/admin/guests/[id]/page.tsx b/app/admin/guests/[id]/page.tsx
index 44025a0..878cb32 100644
--- a/app/admin/guests/[id]/page.tsx
+++ b/app/admin/guests/[id]/page.tsx
@@ -3,6 +3,7 @@ import { notFound } from "next/navigation"
 
 import { CopyInviteButton } from "@/components/admin/copy-invite-button"
 import { DeleteInvitationDialog } from "@/components/admin/delete-invitation-dialog"
+import { InvitationLanguageSelect } from "@/components/admin/invitation-language-select"
 import { Alert, AlertDescription, AlertTitle } from "@/components/ui/alert"
 import { Badge } from "@/components/ui/badge"
 import { Button } from "@/components/ui/button"
@@ -146,6 +147,14 @@ export default async function GuestDetailPage({
             <CardDescription>Admin-managed invitation fields.</CardDescription>
           </CardHeader>
           <CardContent className="space-y-3 text-sm">
+            <div className="space-y-2">
+              <span className="text-muted-foreground">Language</span>
+              <InvitationLanguageSelect
+                invitationId={detail.invitation.id}
+                currentLanguage={detail.invitation.language}
+                displayName={detail.invitation.display_name}
+              />
+            </div>
             <div className="flex justify-between gap-4">
               <span className="text-muted-foreground">Contact email</span>
               <span className="text-right">{detail.invitation.contact_email ?? "—"}</span>
diff --git a/app/admin/guests/actions.ts b/app/admin/guests/actions.ts
index ead413c..58dc2de 100644
--- a/app/admin/guests/actions.ts
+++ b/app/admin/guests/actions.ts
@@ -4,14 +4,25 @@ import { revalidatePath } from "next/cache"
 
 import { auth } from "@/auth"
 import { isAdminEmail } from "@/lib/admin-auth"
-import { updateSaveTheDateSent } from "@/lib/db/queries/invitations"
-import { updateSaveTheDateSentSchema } from "@/lib/validation/invitation"
+import {
+  updateInvitationLanguage,
+  updateSaveTheDateSent,
+} from "@/lib/db/queries/invitations"
+import {
+  updateInvitationLanguageSchema,
+  updateSaveTheDateSentSchema,
+} from "@/lib/validation/invitation"
 
 export interface UpdateSaveTheDateSentResult {
   ok: boolean
   error: string | null
 }
 
+export interface UpdateInvitationLanguageResult {
+  ok: boolean
+  error: string | null
+}
+
 export async function updateSaveTheDateSentAction(input: {
   invitationId: string
   sent: boolean
@@ -49,3 +60,42 @@ export async function updateSaveTheDateSentAction(input: {
 
   return { ok: true, error: null }
 }
+
+export async function updateInvitationLanguageAction(input: {
+  invitationId: string
+  language: string
+}): Promise<UpdateInvitationLanguageResult> {
+  const session = await auth()
+  const adminEmail = session?.user?.email
+
+  if (!isAdminEmail(adminEmail)) {
+    return { ok: false, error: "You are not allowed to update invitations." }
+  }
+
+  const parsed = updateInvitationLanguageSchema.safeParse(input)
+
+  if (!parsed.success) {
+    return { ok: false, error: "Select a supported language." }
+  }
+
+  try {
+    const updated = await updateInvitationLanguage({
+      invitationId: parsed.data.invitationId,
+      language: parsed.data.language,
+      adminEmail: adminEmail ?? "",
+    })
+
+    if (!updated) {
+      return { ok: false, error: "This guest group no longer exists." }
+    }
+  } catch (error) {
+    console.error("Failed to update invitation language", error)
+    return { ok: false, error: "Could not update the invitation language." }
+  }
+
+  revalidatePath(`/admin/guests/${parsed.data.invitationId}`)
+  revalidatePath("/admin/guests")
+  revalidatePath("/admin")
+
+  return { ok: true, error: null }
+}
diff --git a/components/admin/invitation-language-select.tsx b/components/admin/invitation-language-select.tsx
new file mode 100644
index 0000000..b59cf4b
--- /dev/null
+++ b/components/admin/invitation-language-select.tsx
@@ -0,0 +1,90 @@
+"use client"
+
+import { useRouter } from "next/navigation"
+import { useState } from "react"
+
+import { updateInvitationLanguageAction } from "@/app/admin/guests/actions"
+import {
+  Select,
+  SelectContent,
+  SelectItem,
+  SelectTrigger,
+  SelectValue,
+} from "@/components/ui/select"
+import { supportedLanguages } from "@/lib/i18n/config"
+
+interface InvitationLanguageSelectProps {
+  invitationId: string
+  currentLanguage: string
+  displayName: string
+}
+
+export function InvitationLanguageSelect({
+  invitationId,
+  currentLanguage,
+  displayName,
+}: InvitationLanguageSelectProps) {
+  const router = useRouter()
+  const [value, setValue] = useState(currentLanguage)
+  const [message, setMessage] = useState<string | null>(null)
+  const [error, setError] = useState<string | null>(null)
+  const [isSaving, setIsSaving] = useState(false)
+
+  async function updateLanguage(nextLanguage: string) {
+    if (nextLanguage === value) return
+
+    const previousLanguage = value
+
+    setValue(nextLanguage)
+    setMessage(null)
+    setError(null)
+    setIsSaving(true)
+
+    try {
+      const result = await updateInvitationLanguageAction({
+        invitationId,
+        language: nextLanguage,
+      })
+
+      if (!result.ok) {
+        setValue(previousLanguage)
+        setError(result.error)
+        return
+      }
+
+      setMessage("Language updated.")
+      router.refresh()
+    } catch {
+      setValue(previousLanguage)
+      setError("Could not update the invitation language.")
+    } finally {
+      setIsSaving(false)
+    }
+  }
+
+  return (
+    <div className="space-y-2">
+      <Select
+        value={value}
+        disabled={isSaving}
+        onValueChange={(next) => void updateLanguage(next)}
+      >
+        <SelectTrigger
+          aria-label={`Invitation language for ${displayName}`}
+          className="w-full"
+        >
+          <SelectValue placeholder="Select language" />
+        </SelectTrigger>
+        <SelectContent>
+          {supportedLanguages.map((language) => (
+            <SelectItem key={language.code} value={language.code}>
+              {language.label}
+            </SelectItem>
+          ))}
+        </SelectContent>
+      </Select>
+      {message ? <p className="text-xs text-emerald-700">{message}</p> : null}
+      {error ? <p className="text-xs text-destructive">{error}</p> : null}
+    </div>
+  )
+}
diff --git a/lib/db/queries/invitations.ts b/lib/db/queries/invitations.ts
index 3e7b3db..3bed4c4 100644
--- a/lib/db/queries/invitations.ts
+++ b/lib/db/queries/invitations.ts
@@ -191,6 +191,55 @@ export async function updateSaveTheDateSent({
   })
 }
 
+export async function updateInvitationLanguage({
+  invitationId,
+  language,
+  adminEmail,
+}: {
+  invitationId: string
+  language: string
+  adminEmail: string
+}) {
+  return db.transaction().execute(async (trx) => {
+    const invitation = await trx
+      .selectFrom("invitations")
+      .select(["id", "display_name", "language"])
+      .where("id", "=", invitationId)
+      .executeTakeFirst()
+
+    if (!invitation) return null
+
+    const updated = await trx
+      .updateTable("invitations")
+      .set({
+        language,
+        updated_at: new Date(),
+      })
+      .where("id", "=", invitationId)
+      .returning(["id", "language"])
+      .executeTakeFirst()
+
+    if (!updated) return null
+
+    await trx
+      .insertInto("admin_audit_events")
+      .values({
+        admin_email: adminEmail,
+        action: "invitation.language_updated",
+        target_type: "invitation",
+        target_id: invitationId,
+        metadata: {
+          displayName: invitation.display_name,
+          previousLanguage: invitation.language,
+          newLanguage: language,
+        },
+      })
+      .execute()
+
+    return updated
+  })
+}
+
 export async function listInvitations(): Promise<InvitationListItem[]> {
   const invitations = await db
     .selectFrom("invitations")
diff --git a/lib/validation/invitation.ts b/lib/validation/invitation.ts
index bcc9bc9..0ee5ec2 100644
--- a/lib/validation/invitation.ts
+++ b/lib/validation/invitation.ts
@@ -54,6 +54,14 @@ export const updateSaveTheDateSentSchema = z.object({
   sent: z.boolean(),
 })
 
+export const updateInvitationLanguageSchema = z.object({
+  invitationId: z.uuid(),
+  language: z.enum(supportedLanguageCodes, {
+    error: "Select a supported language",
+  }),
+})
+
 export type CreateInvitationInput = z.infer<typeof createInvitationSchema>
 export type DeleteInvitationInput = z.infer<typeof deleteInvitationSchema>
 export type UpdateSaveTheDateSentInput = z.infer<typeof updateSaveTheDateSentSchema>
+export type UpdateInvitationLanguageInput = z.infer<typeof updateInvitationLanguageSchema>