The goal of behavioral intervention in obesity treatment is to help obese individuals adhere to a healthful lifestyle. Its primary strategies include self-monitoring, goal setting, stimulus control, cognitive restructuring, stress management, and social support. Behavioral interventions with follow-ups of >2 years result in initial mean weight losses of about 8-10% and follow-up losses of about 5%. Treatments with the best results include continuous contact throughout the intervention. Multi-component post-treatment programs have shown long-term efficacy. The Look AHEAD study has completed the longest, largest randomized trial with outcome data showing significant efficacy. The study randomized 5,145 obese participants with diabetes to either an intensive lifestyle intervention (N=2,630) or a control group (N=2,574) over 10 years. Behavioral intervention strategies were incorporated to help participants adhere to a healthy diet and physical activity program with a study weight loss goal of 7%. At the year 1 assessment, participants who received the intensive lifestyle intervention had lost an average of 8.6% compared to the control group’s 0.7%. At the year 10 assessment, the intensive lifestyle participants had maintained an average weight loss of 6.0% compared to the control group’s 3.5%. Extended behavioral interventions have shown promise in promoting adherence to the behaviors required for long-term maintenance.