The aim of this study was to analyze the relationship between TV and computer use, study time, and physical activity, with regard to gender, school, and weekday/weekend. Adolescents (N = 1,609; M age = 14.5 yr., SD = 1.3) reported on physical activity, sedentary behavior, their parents' employment, and environmental factors. The relationship between PA and screen media behaviors was negative on weekdays, while no relationship was found at weekends. Only 30.7% of adolescents met the screen media guidelines on weekdays and 14.6% at weekends. Girls spent more time on study, only showing a positive relationship with physical activity on weekdays. Each type of sedentary behavior has different correlates for weekdays and weekends.