Objective. To investigate adolescent eating, activity, and behavioral patterns, and attitudes and their associations with obesity in selected communities in Indonesia. Design. A cross-sectional questionnaire and physical measurement-based study in three communities of varying modernization levels in Indonesia (Yogyakarta, Kuta, and Jakarta). Subjects. 1758 middle school students (aged 12–15 years) recruited at six different schools: one public and one private school in each of the three target communities. Measurements. The questionnaire collected data on demographic characteristics (age, gender, ethnicity, estimated household income); fast food eating habits (frequency, types of food/restaurant, general beliefs about fast foods); television, computer, and Play Station usage; physical activity (hrs/wk of participation in physical activity, transportation means for attending school); and eating habits (frequency of consuming selected foods and beverages). Student's height and weights were obtained, body mass index (BMI: weight [kg]/height [m2]) was calculated, and obesity was defined as ≥95%, using the BMI-for-age cut-offs from the Centers for Disease Control and Prevention (CDC) charts. Results. Chi-square analysis revealed associations between obesity and community setting, family income, use of a computer or Play Station, type of transportation to school, and beliefs about fast foods (PConclusion. Greater likelihood of obesity among Indonesian adolescents who spend greater amounts of time using a computer or Play Station suggests that such sedentary activities may be replacing physical activity, promoting an energy imbalance, and subsequently, an increased risk for obesity.