The present research program began as a preliminary attempt to examine the relationship between client and treatment loci of control as a predictor of success in weight control programs. In the first phase of the research, individuals previously attempting weight loss, and the programs they had pursued, were classified as being either primarily internally-oriented or externally-oriented. Retrospective analysis of their experiences revealed more weight loss for those whose locus of control orientation was similar to that of their program. Successive replications, however, generated data suggesting that a more powerful predictive factor may be whether the individual pursued a self-directed weight management program or sought formal treatment. In particular, for the 66 college students participating in the three phases of the research, it was found that those whose weight control efforts were self-managed lost weight at more than twice the rate (2.47 pounds per week) as those who had entered formal treatment programs (1.22 pounds per week). These findings suggest the potential value of efforts to delineate factors and mechanisms involved in the successful management of habit problems. (Author)