Obesity has reached epidemic proportions globally and the prevention of adult obesity will require prevention and management of childhood obesity. A study was conducted to determine the prevalence and behavioral determinants of overweight and obesity in school going adolescents. A total of 660 adolescents from affluent and nonaffluent schools were taken. Overweight and obesity was defined as per World Health Organization 2007 growth reference. Prevalence of overweight and obesity was 9.8% and 4.8%, respectively. Prevalence of both overweight and obesity was higher among males. Statistically significant difference was found in prevalence of overweight and obesity among affluent schools (14.8% and 8.2%) and nonaffluent schools (4.8% and 1.5%). Important determinants of overweight and obesity were increased consumption of fast food, low physical activity level and watching television for more than 2 h/day. The prevalence of obesity is high even in small cities. Dietary behavior and physical activity significantly affect weight of adolescent children.