This study examined the association between self-reported physical activity and a number of potential correlates in a sample of 256 Grade 6 children. Physical activity was assessed in both summer and winter, and children and parents completed questionnaires assessing potential correlates of physical activity. Analyses revealed that gender, time spent playing outside, self-efficacy in overcoming barriers, and number of items of exercise equipment at home were variables associated with physical activity in both seasons. School location was a variable associated with physical activity only in the summer, whereas private-lesson attendance, sports-club attendance, and best friend's physical activity were variables associated with physical activity only in winter. Variance explained in physical activity were 42% and 51% in winter and summer, respectively.