Objective: This study aimed to identify intrapersonal, interpersonal, and environmental correlates of leisure-time participation in sports and examine whether they are also associated with screen-time among adolescents. Methods: Adolescents from eight schools in Victoria, Australia were recruited for this study. Participants (n = 400) comprised of an even distribution of boys (51%) and girls (49%) aged 12-16 years. Their engagement in leisure-time activities (including sports and screen-time) and 13 potential correlates were self-reported. Multinomial logistic regression analyses examined correlates of sports and screen-time participation categories, accounting for clustering by school and adjusting for significant sociodemographic characteristics. Results: The majority (76%) participated in leisure-time sports and exceeded screen-time recommendations (<2 h/day) on both weekdays (69%) and weekend days (85%). Greater internal motivation for sports was positively associated with sports participation and inversely associated with screen-time on weekend days, respectively. Fewer barriers, positive family and coach support and more neighborhood sporting opportunities were significantly associated with greater sports participation. Neighborhood social norms were inversely associated with sports participation. Preference for sports was associated with less weekday and weekend screen-time. Friend support for sports was inversely associated with weekday screen-time. Access to sports facilities in the local neighborhood was associated with more weekday and weekend screen-time. Conclusion: Internal motivation for sports was associated with both sports participation and less screen-time. Preference for leisure-time sports and friend support for sports were associated with less screen-time. Future research should continue to explore common correlates of multiple leisure-time behaviors to inform the development of effective intervention strategies.