Understanding physical activity (PA) correlates in youth is challenging due to the inherent changes in activity patterns, activity preferences, and social norms that occur during the normal developmental transition from childhood into adolescence. This study examines possible age-related differences in physical activity correlates using the Children’s Physical Activity Correlates Scale (CPAC). The Children’s Physical Activity Questionnaire (PAQ) was used to measure typical levels of PA. Results indicate high school youth had lower levels of PA and lower levels on the psychosocial correlates than middle school youth. Parental influence accounted for ~ 15% of the variance in PA while the predisposing factors (perceived competence, attraction to PA) accounted for 20% and 17% of the variance for middle and high school students, respectively. CPAC has similar predictive validity across the age range. The CPAC scale offers potential to help understand factors that influence physical activity behavior during the transition from childhood into adolescence.