Habituation is one factor that may be related to excess energy intake. Research has shown that the rate of habituation is inversely related to the amount of food consumed and slower habituation may be a factor that is relevant to obesity, as overweight youth and adults habituate slower and consume more energy than their peers. Habituation is a basic form of learning that is observed in many response systems. We believe that habituation is an important process that mediates food regulation during a meal and across meals. However, there has been no research in children that translates basic research on habituation to food into clinical interventions for pediatric obesity. In the first phase, we will implement a series of laboratory studies to assess the effects of stimulus specificity and variety and the simultaneous reduction of variety for high energy density foods on short (within meal) and long-term (across meal) habituation. The second phase is designed to implement a series of field studies that will extend basic research from the first phase as well as define the optimal interval for reducing variety to facilitate long-term habituation to high energy density foods in the natural environment. The third phase is designed to develop and pilot test a family-based behavioral intervention for children that incorporates findings from phase2 into a clinical intervention.