Background: Arthroscopic treatment of posterior shoulder instability has become more popular and effective in recent years, but few data are available concerning the rate of return to sport. Purpose: To present our experiences with arthroscopic posterior labral reconstruction in athletes and review our results, with a particular focus on the rate of return to sport. Study Design: Case series; Level of evidence, 4. Methods: Included in the study were 40 arthroscopic stabilizations performed because of posterior shoulder instability in 37 athletes at a single institution. During follow-up, the athletes’ rate of return to sport was calculated. Shoulder function was evaluated based on a pre- versus postoperative comparison of the Rowe instability score and the American Shoulder and Elbow Surgeons score. Additionally, the return-to-sport rate was compared among different subgroups: traumatic versus atraumatic origin of injury, competitive versus recreational athletes, high-risk versus low-risk sport, and posterior-only versus anterior and posterior stabilization. Data were statistically analyzed using paired-samples t test and nonparametric Fisher exact test. Results: The average follow-up period was 54.4 months (range, 24-112 months). Three shoulders (7.5%) continued to have posterior subluxations postoperatively. There were 34 excellent, 3 good, and 3 fair results based on the Rowe score (average postoperative score, 92.9), and patients achieved an average postoperative American Shoulder and Elbow Surgeons score of 92.7. The pre- to postoperative improvement was statistically significant in both scoring systems ( P < .001). Of the 37 patients, 36 (98.2%) were able to return to sport activity: 27 of them (72.9%) to their original sport and 19 (51.4%) at their preinjury level. A significantly higher rate of return to the same sport occurred in athletes who had traumatic injury compared with a subgroup of athletes without a traumatic event ( P < .02). Conclusion: More than half of the athletes were able to return to their preinjury level of sport after arthroscopic posterior labral reconstruction. In addition, low recurrence rates and good functional outcomes were seen in >90% of the patients, and 98% returned to sport activity. The athletes had a significantly higher rate of return to sport if their posterior shoulder instability had a clear traumatic origin.