Weight-loss history was examined as a predictor of outcome in group self-help obesity treatment. Participants (n = 128; 83% women; mean body mass index = 34.2 kg/m²; mean age = 47.2 years) in self-help, group behavioral weight-loss treatment reported a mean of 5.1 prior weight-loss attempts and lost 13.8 percent of initial weight in current treatment. A greater number of past attempts independently predicted greater 6-month, 18-month, and intent-to-treat weight losses. Greater magnitude of largest past loss predicted greater 18-month weight loss. In contrast to studies on professional treatment, group self-help participants might benefit from repeated weight-loss efforts despite previous failures.