The aim was to examine the effects of a multicomponent school-based intervention on psychological correlates of physical activity (PA) in physical education (PE) and leisure-time PA settings. Two hundred and ten students (M = 13.06 ± 0.61) were assigned either to a control or an experimental school. Curricular and extracurricular PA actions were developed during one academic year to empower adolescents to be active by themselves. Experimental school students reported significant improvements in almost all psychological determinants and correlates of PA in PE and leisure-time PA settings, when compared to both control school students and their own baseline values. Results highlight the importance of developing multicomponent school-based interventions that involve the school community to improve students' motivational outcomes in PE and leisure-time PA contexts.