Background: During 1978 and 1979, we initiated a prospective multicenter study to evaluate the results of nonoperative treatment of primary anterior shoulder dislocation. In the current report, we present the outcome after twenty-five years. Methods: Two hundred and fifty-five patients (257 shoulders) with an age of twelve to forty years who had a primary anterior shoulder dislocation were managed with immobilization (achieved by tying the arm to the torso with use of a bandage) or without immobilization. All 227 living patients (229 shoulders) completed the follow-up questionnaire, and 214 patients completed the Disabilities of the Arm, Shoulder and Hand (DASH) questionnaire. Results: Ninety-nine (43%) of 229 shoulders had not redislocated, and seventeen (7%) redislocated once. Thirty-three recurrent dislocations had become stable overtime (14.4%), and eighteen were considered to be still recurrent (7.9%). Sixty-two shoulders (27%) had undergone surgery for the treatment of recurrent instability. Immobilization after the primary dislocation did not change the prognosis. Only two of twenty-four shoulders with a fracture of the greater tuberosity at the time of the primary dislocation redislocated (p < 0.001). When shoulders with a fracture of the greater tuberosity were excluded, forty-four (38%) of 115 shoulders in patients who had been twelve to twenty-five years of age at the time of the original dislocation and sixteen (18%) of ninety shoulders in patients who had been twenty-six to forty years of age had undergone surgical stabilization. At twenty-five years, fourteen (23%) of sixty-two shoulders that had undergone surgical stabilization were in patients who subsequently had a contralateral dislocation, compared with seven (7%) of ninety-nine shoulders in patients in whom the index dislocation had been classified as solitary (p = 0.01). Gender and athletic activity did not appear to affect the redislocation rate, however, women had worse DASH scores than men did (p = 0.006). Conclusions: After twenty-five years, half of the primary anterior shoulder dislocations that had been treated nonoperatively in patients with an age of twelve to twenty-five years had not recurred or had become stable over time. Level of Evidence: Prognostic Level I. See Instructions to Authors for a complete description of levels of evidence. Copyright © 2008 by the Journal of Bone and Joint Surgery, Incorporated.