Objective: The primary goal of the paper is to examine the contribution of time spent in front of screens, self-assessed mental health and place of residence in explaining total physical activity and physical activity of different levels in relation to place of residence. Additionally, we wanted to examine the connection between self-assessment of adolescent mental health, their level of physical activity and tendency to sedentary behavior in the form of using various screens. The purpose was to examine the connection between mental health and psychological difficulties with levels of physical activity and sedentary behavior and place of residence. The secondary aim of the work refers to the validation of the Croatian version of the Strengths and Difficulties Questionnaire (Bøe et al., 2016; Ortuño-Sierra et al., 2018; Svedin and Priebe, 2008), SDQ-Cro. Methods: The research includes 244 adolescents from secondary schools in Zadar. The level of physical activity was assessed with two items of the SHAPES questionnaire, which are aimed at a seven-day observation of moderate or intense physical activity, as well as sedentary behavior, that is, the time spent in front of screens. Mental health was assessed with the Croatian version of the SDQ questionnaire, which contains 18 items grouped into four dimensions related to emotional problems, behavioral problems, hyperactivity and prosocial behavior. Results: Students in both areas were found to meet criteria for physical activity on a daily basis, particularly in moderate-intensity activities, while greatly exceeding the recommended screen time. Differences for these variables in relation to place of residence have not been established. Also, self-rated mental health, screen time, and residence were found not to predict physical activity level for this sample and that an insufficient level of vigorous physical activity is associated with more pronounced emotional difficulties.