Shoulder instability is based on various acquired or constitutional aspects which determine the therapy and clinical outcome. In order to differentiate between traumatic and atraumatic forms of shoulder instability a careful history has to be taken. A systematic clinical examination is necessary to evaluate the shoulder joint for general laxity or true instability and especially to assess direction and degree of glenohumeral translation. The basic diagnostic imaging includes X-rays in 3 planes. CT-arthrogram and MRI may provide additional information to evaluate the intraarticular pathology. An elective therapy depends on the patients age and demands. Recurrent anterior dislocations are treated by an anatomical reconstruction of the glenohumeral ligament complex. Open or arthroscopic Bankart-repair have been established as the treatment of choice. Conservative treatment is primarily indicated in cases of atraumatic posterior or multidirectional instability. If physiotherapy fails, surgical treatment should be discussed for these patients.