This study used a theoretical framework with multiple variables in multivariate analyses (factor, multiple regression, and path analyses) to investigate the sociopsychological predictors of weight loss. Responses from 309 participants of a comprehensive weight-loss program indicated that self-assurance was the most significant predictor of actual weight loss, followed by weeks completed. Other factors, such as program satisfaction and perceived importance, indirectly predicted weight loss through the intervening variables of self-assurance and weeks completed. Differences in the factors predicting weight loss were observed between completers and dropouts. The implications of these results for professionals concerned with weight control are discussed.