The 4-item Weight Locus of Control (WLOC) scale is a specific measure of expectancies for locus of control with respect to personal weight developed for the prediction of behaviors in relation to weight reduction. Normative data on the WLOC scale are presented. Two studies show discriminant validity of the WLOC scale in contrast with other published measures of locus of control. In Study 1, the predicted relative importance of personal attitudes toward losing weight and of social pressures for weight loss in determining intentions to lose weight was achieved for WLOC internals and externals who valued health and/or physical appearance highly. In Study 2, subjects beginning a weight control program who were categorized as internal on the WLOC scale were more likely to complete the program than WLOC externals. Additionally, program completers who were internal on the WLOC scale and who highly valued health or physical appearance were more successful in achieving their initial weight loss goals than program ...