The diagnosis and treatment of shoulder instability are predicated on a sound understanding of the patient's history and injury pattern as well as the examination and radiographic findings. The arthroscopic repair of instability is increasingly successful. However, glenohumeral bone loss, capsular injuries, and associated injury patterns have been linked to unsuccessful outcomes after either surgical or nonsurgical treatment. A comprehensive approach, from patient history to surgical technique, can increase the likelihood of a successful primary or secondary instability repair.