Community service activities in the field of internal audit are carried out in the Satya Wacana Christian High School to assess the existing 3E (efficient, effective, and economical). The methods in this internal audit activity include identifying risks, audit programs and procedures, interviewing, observing, confirming, distributing questionnaires, and providing recommendations based on audit findings. The results if this activity are in the form of recommendations for prevention, improvement of the library operational activitiesbased of the 3E principle.