A physical/sports activity is important for individual's motor skill and psychological development. It enables one to gather new experiences, select information from the environment and apply them in different life situations. The paper gives an overview of correlates related to physical activity of children and adolescents. Based on the analysis of the available literature, these correlates can be classified in the following groups: demographic and biological, psychological, social and environmental. We presented recent research findings for each group of correlates and emphasized their importance for active living of children and youth. The study of correlates of physical activity often resulted in inconsistent and inconclusive findings. The reasons for this lie in several methodo-logical shortcomings - the use of different methods and instruments. The paper also highlights the need for establishing links between the correlates and different forms of physical activity and determining their impact in specific social contexts.