diff --git a/backend/app/api/v1/routes_language_qc.py b/backend/app/api/v1/routes_language_qc.py
index e3c60c0..6fc0dfe 100644
--- a/backend/app/api/v1/routes_language_qc.py
+++ b/backend/app/api/v1/routes_language_qc.py
@@ -8,9 +8,11 @@ from pydantic import BaseModel, Field
 
 from ...core.database import get_database
 from ...core.dependencies import require_roles
+from ...models.audit_log import AuditAction
 from ...models.job import LanguageQCComment, LanguageQCState
 from ...models.user import User, UserRole
 from ...services import language_qc as lqc
+from ...services.audit_logger import audit_logger
 
 router = APIRouter(tags=["language-qc"])
 
@@ -131,6 +133,15 @@ async def assign_language(
         db, job_id, lang, request.linguist_user_id, current_user,
         http_request=http_request, notes=request.notes, deadline=request.deadline,
     )
+    await audit_logger.log_action(
+        action=AuditAction.LANGUAGE_QC_ASSIGN,
+        description=f"Language '{lang}' assigned to linguist '{request.linguist_user_id}' for job {job_id}",
+        user=current_user,
+        request=http_request,
+        resource_type="job",
+        resource_id=job_id,
+        details={"lang": lang, "linguist_user_id": request.linguist_user_id},
+    )
     return LanguageQCStateResponse(lang=lang, state=state)
 
 
@@ -149,6 +160,15 @@ async def reassign_language(
         db, job_id, lang, request.linguist_user_id, current_user,
         http_request=http_request, notes=request.notes, deadline=request.deadline,
     )
+    await audit_logger.log_action(
+        action=AuditAction.LANGUAGE_QC_REASSIGN,
+        description=f"Language '{lang}' reassigned to linguist '{request.linguist_user_id}' for job {job_id}",
+        user=current_user,
+        request=http_request,
+        resource_type="job",
+        resource_id=job_id,
+        details={"lang": lang, "linguist_user_id": request.linguist_user_id},
+    )
     return LanguageQCStateResponse(lang=lang, state=state)
 
 
@@ -169,6 +189,15 @@ async def assign_reviewer(
         db, job_id, lang, request.reviewer_user_id, current_user,
         http_request=http_request, notes=request.notes, deadline=request.deadline,
     )
+    await audit_logger.log_action(
+        action=AuditAction.LANGUAGE_QC_REVIEWER_ASSIGN,
+        description=f"Reviewer '{request.reviewer_user_id}' assigned to language '{lang}' for job {job_id}",
+        user=current_user,
+        request=http_request,
+        resource_type="job",
+        resource_id=job_id,
+        details={"lang": lang, "reviewer_user_id": request.reviewer_user_id},
+    )
     return LanguageQCStateResponse(lang=lang, state=state)
 
 
@@ -187,6 +216,15 @@ async def reassign_reviewer(
         db, job_id, lang, request.reviewer_user_id, current_user,
         http_request=http_request, notes=request.notes, deadline=request.deadline,
     )
+    await audit_logger.log_action(
+        action=AuditAction.LANGUAGE_QC_REVIEWER_REASSIGN,
+        description=f"Reviewer reassigned to '{request.reviewer_user_id}' for language '{lang}', job {job_id}",
+        user=current_user,
+        request=http_request,
+        resource_type="job",
+        resource_id=job_id,
+        details={"lang": lang, "reviewer_user_id": request.reviewer_user_id},
+    )
     return LanguageQCStateResponse(lang=lang, state=state)
 
 
@@ -248,6 +286,21 @@ async def bulk_assign_languages(
 
         assigned.append(lang)
 
+    await audit_logger.log_action(
+        action=AuditAction.LANGUAGE_QC_BULK_ASSIGN,
+        description=f"Bulk assignment for job {job_id}: {len(assigned)} language(s) assigned to linguist '{request.linguist_user_id}'",
+        user=current_user,
+        request=http_request,
+        resource_type="job",
+        resource_id=job_id,
+        details={
+            "languages": assigned,
+            "linguist_user_id": request.linguist_user_id,
+            "reviewer_user_id": request.reviewer_user_id,
+            "skipped": skipped,
+            "errors": errors,
+        },
+    )
     return BulkAssignResponse(assigned=assigned, skipped=skipped, errors=errors)
 
 
@@ -265,6 +318,15 @@ async def start_linguist_work(
 ):
     """Linguist opens the language — pending → in_progress."""
     state = await lqc.start_linguist_work(db, job_id, lang, current_user)
+    await audit_logger.log_action(
+        action=AuditAction.LANGUAGE_QC_START_WORK,
+        description=f"Linguist started work on language '{lang}' for job {job_id}",
+        user=current_user,
+        request=http_request,
+        resource_type="job",
+        resource_id=job_id,
+        details={"lang": lang},
+    )
     return LanguageQCStateResponse(lang=lang, state=state)
 
 
@@ -280,6 +342,15 @@ async def submit_for_review(
 ):
     """Linguist submits — in_progress → pending_review. Notifies reviewer by email."""
     state = await lqc.submit_for_review(db, job_id, lang, current_user, http_request=http_request)
+    await audit_logger.log_action(
+        action=AuditAction.LANGUAGE_QC_SUBMIT,
+        description=f"Language '{lang}' submitted for review for job {job_id}",
+        user=current_user,
+        request=http_request,
+        resource_type="job",
+        resource_id=job_id,
+        details={"lang": lang},
+    )
     return LanguageQCStateResponse(lang=lang, state=state)
 
 
@@ -295,6 +366,15 @@ async def open_review(
 ):
     """Reviewer opens the review — pending_review → in_review."""
     state = await lqc.open_review(db, job_id, lang, current_user, http_request=http_request)
+    await audit_logger.log_action(
+        action=AuditAction.LANGUAGE_QC_OPEN_REVIEW,
+        description=f"Reviewer opened review for language '{lang}', job {job_id}",
+        user=current_user,
+        request=http_request,
+        resource_type="job",
+        resource_id=job_id,
+        details={"lang": lang},
+    )
     return LanguageQCStateResponse(lang=lang, state=state)
 
 
@@ -314,6 +394,15 @@ async def approve_language(
     state = await lqc.approve_language(
         db, job_id, lang, current_user, http_request=http_request, notes=request.notes,
     )
+    await audit_logger.log_action(
+        action=AuditAction.LANGUAGE_QC_APPROVE,
+        description=f"Language '{lang}' approved for job {job_id}",
+        user=current_user,
+        request=http_request,
+        resource_type="job",
+        resource_id=job_id,
+        details={"lang": lang, "notes": request.notes},
+    )
     return LanguageQCStateResponse(lang=lang, state=state)
 
 
@@ -331,6 +420,15 @@ async def reject_language(
     state = await lqc.reject_language(
         db, job_id, lang, current_user, request.notes, category=request.category, http_request=http_request,
     )
+    await audit_logger.log_action(
+        action=AuditAction.LANGUAGE_QC_REJECT,
+        description=f"Language '{lang}' rejected for job {job_id}",
+        user=current_user,
+        request=http_request,
+        resource_type="job",
+        resource_id=job_id,
+        details={"lang": lang, "notes": request.notes, "category": request.category},
+    )
     return LanguageQCStateResponse(lang=lang, state=state)
 
 
@@ -343,6 +441,7 @@ async def mark_cue_reviewed(
     job_id: str,
     lang: str,
     request: MarkCueReviewedRequest,
+    http_request: Request,
     current_user: User = Depends(require_roles(UserRole.REVIEWER, UserRole.ADMIN)),
     db: AsyncIOMotorDatabase = Depends(get_database),
 ):
@@ -363,6 +462,19 @@ async def mark_cue_reviewed(
     state_dict = (updated_doc.get("language_qc") or {}).get(lang, {})
     from ...models.job import LanguageQCState
     state = LanguageQCState(**state_dict) if isinstance(state_dict, dict) else LanguageQCState()
+    await audit_logger.log_action(
+        action=AuditAction.LANGUAGE_QC_MARK_CUE_REVIEWED,
+        description=f"Cue marked as reviewed for language '{lang}', job {job_id}",
+        user=current_user,
+        request=http_request,
+        resource_type="job",
+        resource_id=job_id,
+        details={
+            "lang": lang,
+            "reviewed_cues": state.reviewed_cues if hasattr(state, "reviewed_cues") else None,
+            "total_cues": request.total_cues,
+        },
+    )
     return LanguageQCStateResponse(lang=lang, state=state)
 
 
@@ -378,6 +490,15 @@ async def reopen_language(
     state = await lqc.reopen_language(
         db, job_id, lang, current_user, http_request=http_request, notes=request.notes,
     )
+    await audit_logger.log_action(
+        action=AuditAction.LANGUAGE_QC_REOPEN,
+        description=f"Language '{lang}' reopened for job {job_id}",
+        user=current_user,
+        request=http_request,
+        resource_type="job",
+        resource_id=job_id,
+        details={"lang": lang, "notes": request.notes},
+    )
     return LanguageQCStateResponse(lang=lang, state=state)
 
 
@@ -398,6 +519,15 @@ async def add_comment(
     comment = await lqc.add_comment(
         db, job_id, lang, current_user, request.body, http_request=http_request,
     )
+    await audit_logger.log_action(
+        action=AuditAction.LANGUAGE_QC_COMMENT,
+        description=f"Comment added to language '{lang}' for job {job_id}",
+        user=current_user,
+        request=http_request,
+        resource_type="job",
+        resource_id=job_id,
+        details={"lang": lang, "comment_id": str(comment.id) if hasattr(comment, "id") else None},
+    )
     return comment