Background:Glenohumeral instability is a common abnormality, especially among athletes. Previous studies have evaluated outcomes after arthroscopic stabilization in patients with anterior or posterior shoulder instability but have not compared outcomes between groups.Purpose:To compare return-to-sport and other patient-reported outcomes in patients after primary arthroscopic anterior, posterior, and combined anterior and posterior shoulder stabilization.Study Design:Cohort study; Level of evidence, 3.Methods:Patients who underwent primary arthroscopic anterior, posterior, or combined anterior and posterior shoulder stabilization were contacted at a minimum 2-year follow-up. Patients completed a survey that consisted of return-to-sport outcomes as well as the Western Ontario Shoulder Instability Index (WOSI), Single Assessment Numeric Evaluation (SANE), American Shoulder and Elbow Sur’geons (ASES) score, and Shoulder Activity Scale.Results:A total of 151 patients were successfully contacted (anterior: n = 81; posterior: n = 22; combined: n = 48) at a mean follow-up of 3.6 years. No significant differences were found between the groups with regard to age at the time of surgery or time to follow-up. No significant differences were found between the groups in terms of WOSI (anterior: 76; posterior: 70; combined: 78; P = .28), SANE (anterior: 87; posterior: 85; combined: 87; P = .79), ASES (anterior: 88; posterior: 83; combined: 91; P = .083), or Shoulder Activity Scale (anterior: 12.0; posterior: 12.5; combined: 12.5; P = .74) scores. No significant difference was found between the groups in terms of the rate of return to sport (anterior: 73%; posterior: 68%; combined: 75%; P = .84).Conclusion:Athletes undergoing arthroscopic stabilization of anterior, posterior, or combined shoulder instability can be expected to share a similar prognosis. High patient-reported outcome scores and moderate to high rates of return to sport were achieved by all groups.