Obesity is a risk factor for a number of adverse medical and psychosocial outcomes. Solving the obesity problem will require a much greater emphasis on prevention. Treatment research indicates that interventions focusing directly on the food environment (structured meals and control of food stimuli) have considerable promise for weight control. Prevention research has found little support for trying to modify characteristics (e.g., knowledge, beliefs, skills) of individuals, perhaps because this approach does little to modify the food environment. The research will be implemented in a workplace cafeteria where employees eat year-round and where the nutritional composition of the food can be modified.