Posterior labral injuries and posterior shoulder instability are becoming an increasingly recognized and treated entity in those with shoulder pain. Arthroscopic stabilization may be performed in either the beach chair or lateral decubitus position. We will describe in detail the arthroscopic technique of posterior labral repair in the beach chair position for the treatment of symptomatic posterior labral lesions or posterior instability in patients who have failed conservative treatment. Postoperative rehabilitation and clinical results will be summarized.