Objectives: Posterior shoulder instability is a diagnostic challenge and a poorly understood clinical problem. Due to the complexity and relative infrequency of diagnosis, several surgical techniques have been described to treat this disorder. The purposes of this study are to retrospectively evaluate arthroscopic posterior shoulder stabilization using a suture-anchor fixation technique, and to evaluate multiple preoperative and intraoperative variables as predictors of outcome. Materials and Methods: Thirty-five patients who underwent posterior arthroscopic shoulder stabilization with either suture anchors and/or suture plication from October 1999 through December 2002 were reviewed. All but one was male, all but one were active duty military, and the mean age was 25.5. Seven had failed prior surgical intervention. Demographic data was obtained, to include duration of symptoms, number and type of conservative modalities, preoperative evaluation of shoulder range of motion, translation, and instability testing. Shoulder outcomes rating scores were determined using the American Shoulder and Elbow Surgeons Rating Scale (ASES), the Western Ontario Shoulder Instability Index (WOSI), the Subjective Patient Shoulder Evaluation, and the Single Assessment Numeric Evaluation (SANE). Results: Mean follow-up was 25 months. Overall, symptoms were improved and outcomes scores rated as good or excellent in 31 of 36 shoulders. Preoperative versus postoperative range of motion examination demonstrated improved values for flexion (172° vs. 165°, P > .05) and abduction (168° vs. 158°, P > .05). The amount of posterior translation averaged +3.4 (range 3+ to 4+) preoperatively versus +1.1 postoperatively (range 0+ to 2+), P < .001. There were five failures in the group medically separated from the military. Conclusions: The arthroscopic treatment of posterior shoulder instability is an effective means to improve symptoms associated with recurrent posterior subluxation of the shoulder. Careful attention to surgical technique and an understanding of the underlying pathology are critical for success.