There has been increased interest in the development and implementation of physical activity interventions designed to increase young people's physical activity participation in recent years. This is perhaps founded on concerns over youngsters' physical activity levels and the possible health consequences. School-based interventions are the most common form of intervention but, given that the majority of young people's physical activity occurs outside school, there is now growing recognition of the importance of community-based programmes and the involvement of the community at all levels if interventions are to be effective. Based on previous reviews of the findings of formally evaluated interventions, this article considers the evidence base for the effectiveness of school and community-based physical activity interventions. Despite limitations in the literature, it reveals that physical activity interventions with young people can be effective and achieve positive outcomes. The interventions are discussed and a number of issues and observations are highlighted concerning the programme types, target populations, and their design and implementation. Based on this discussion, a number of recommendations for physical activity promotion practice are then made. The article concludes that, until a stronger evidence base becomes available, health professionals, physical educators and other practitioners should be encouraged to plan, implement and evaluate physical activity programmes for young people and draw on such recommendations to inform their practice. (Contains 1 table.)