Objective: Environmental factors and behaviors associated with obesity have not been well described in children living in Europe. Although television watching has been repeatedly associated with obesity, it is unclear whether other sedentary activities, such as use of electronic games, are independently associated with obesity in children. The hypothesis was that various types of sedentary activities are associated with obesity in children living in Switzerland. Research Methods and Procedures: This was a cross-sectional study of children (grades one to three) from four communities in the Greater Zurich Area (Switzerland). Obesity was defined as a combination of overweight (BMI) and overfat (skinfold thicknesses). Environmental factors were assessed by questionnaire. The children's physical activity was estimated by their teacher (scale 0 to 10). Results: Of 922 eligible subjects, 872 (94.6%) took part in the study. Use of electronic games [odds ratio (OR) = 2.03 per hour per day, 95% confidence interval (Cl): 1.57 to 2.61, p < 0.001], television (OR = 2.83 per hour per day, 95% CI: 2.08 to 3.86, p < 0.001), physical activity (OR = 0.80 per unit, 95% CI: 0.72 to 0.88, p < 0.001), maternal work (OR = 1.93, 95% Cl: 1.13 to 3.29, p = 0.02), and paternal smoking (OR = 1.78, 95% CI: 1.07 to 2.96, p = 0.03) were independently associated with obesity. Further adjustment for socioeconomic status, when available, did not change these results. Discussion: In this sample of children living in Switzerland, the use of electronic games was significantly associated with obesity, independently of confounding factors. The association of obesity with television use and lack of physical activity confirms results from other populations and points to potential strategies for obesity prevention.