Purpose: The goals were to investigate whether extracurricular school-based sports reach students not engaging in community sports and whether extracurricular school-based sports participants are more physically active and/or autonomously motivated toward sports than nonparticipants. Method: 1526 students (48.0% boys; 85.9% Belgian natives; age = 15.34 ± 1.83y) completed validated questionnaires to assess sports participation, physical activity (PA) and sports-motivation. Multilevel regression analyses were conducted. Results: Only 28.7% of all students (n = 438), and 19.7% of students not engaging in community sports (n = 123), participated in extracurricular school-based sports. Participants were significantly more physically active [ß=44.19, S.E.=17.34, ?[superscript 2](1)=6.50, p = 0.01] and autonomously motivated [ß=0.18, S.E.=0.04, ?[superscript 2](1)=25.62, p < 0.001] than nonparticipants, even after controlling for community sports participation. Boys were more physically active and autonomously motivated than girls (p < 0.001). Conclusion: As participation is linked to higher PA-levels and autonomous motivation, increasing overall participation rates may contribute to children developing a more physically active lifestyle and achieving the PA guidelines.