A treatment program was designed to enable 5s to lose weight through the use of self-monitore d techniques for changing their eating behaviors. All 5s who participated in the program achieved a stable loss in weight, and their mean loss was significantly greater than the change shown by a group of similarly motivated control 5s. No additional effects due to a few sessions of aversive counterconditioning were demonstrated, and no general mood changes accompanied the weight loss, The 5s did report a decreased temptation to overeat. It was suggested that similar programs of gradual habit change through self-control of stimulus conditions and reinforcement contingencies might be applied to the treatment of other addictive behaviors, which are also very refractory to change. Attempts to deal with the undesirable behavior of overeating have been spectacularly unsuccessful. Although a great number of causal agents or correlates have been postulated, such as depression (Simon, 1963), anxiety (Cauffman & Pauley, 1961), power orientation (Suczek, 19S7), a variety of other personality problems (Bruch, 1957; Kaplan & Kaplan, 1957, who list 28 suggested meanings of obesity; Shipman & Plesset, 1963), insufficient exercise (Mayer, 1955), presence of night-eating syndrome (Stunkard, 1959a), lack of correlation between report of hunger and gastric motility (Stunkard, 1959b), obesity of parents (Cappon, 1958), more dependence on external stimuli such as flavors and time of day to regulate hunger (Schachter, 1967), and no doubt many others, no clear causal relationships have been substantially detailed. An equally large variety of treatments have been tried, ranging from such nonacademic means as low-calorie products, exercise salons, yoga, and reducing clubs to hypnosis (Erickson, 1960), dietary instruction (Young, Moore, Berresford, Binset, & Waldner, 1955), appetite depressants and other drugs (Silverstone & Solomon, 1965), general medical advice (Stunkard,