The spectrum of disease in shoulder instability ranges from pain due to instability to locked dislocations. The natural history, treatment, and prognosis differ according to the diagnosis. Anterior glenohumeral (GH) dislocation is the common first-time presentation of shoulder instability that is encountered by clinicians. GH dislocations account for about 50% of all joint dislocations, 95% to 97% of these being anterior dislocations. The inherent mobility of the GH joint comes at the expense of stability. Both static and dynamic restraints afford GH stability. Static restraints include the glenoid labrum, glenohumeral ligaments, articular concavity of the glenoid fossa, and intra-articular pressure. Dynamic restraints include the rotator cuff muscles, periscapular muscles, and biceps tendon. Closed reduction of acute dislocations should be performed in a timely manner. Further diagnostic workup and long-term management are guided by patient age, patient activity level, and mechanism of injury.