Posterior glenohumeral instability in overhead athletes presents a unique set of challenges for both diagnosis and treatment. Although a great deal of attention has been focused on the management of injuries to the biceps-labrum complex and rotator cuff in throwers, comparatively less has been written about posterior glenohumeral instability within this unique cohort. Historically, posterior instability has been observed secondary to either acute trauma or repetitive microtrauma, usually among collision athletes, weight lifters, and rowers. However, posterior glenohumeral instability resulting from pathology of the posterior capsulolabral tissues in throwers is a different entity, and the clinical assessment begins with an accurate differentiation between adaptive capsular laxity and labral injury with pathologic instability. Some posterior capsule labrum tears confirmed on arthroscopy will require nothing more than débridement. However, for more extensive lesions, surgical treatment must balance the necessity to repair torn capsulolabral tissues with the tendency to over constrain the shoulder. The literature provides mixed results regarding the likelihood of overhead athletes with posterior glenohumeral instability and labral injury treated surgically returning to their preinjury level of sport performance.