The term "shoulder instability" constitutes a spectrum of disorders that includes dislocation, subluxation and laxity. Anterior instability is the most common form of glenohumeral instability and may be associated with nerve injury. The diagnosis of anterior, posterior or multidirectional instability is based on a thorough history and physical examination that includes specific provocative maneuvers. The load-and-shift test, the relocation test, the drawer test, the sulcus test and the anterior apprehension test are useful for assessment of the shoulder. Radiographic studies should include special views to delineate specific lesions, such as a Bankart lesion and a Hill-Sachs defect. Early surgical intervention may be a consideration, especially in younger patients. Recent studies suggest that surgical intervention after the first dislocation may reduce the rate of recurrence. Rehabilitation is accomplished in four phases, beginning with rest and pain control and proceeding to isometric and isotonic exercises. The goal is for the patient to reach 90 percent strength in the injured shoulder compared with the uninjured shoulder.