The increasing prevalence of obesity among the world's children and youth was the impetus for an international conference convened in Toronto, Canada, to examine issues related to physical activity and obesity in children (24-27 June 2007). The goal of the conference was to assimilate, interpret, and share scientific evidence with key stakeholders to develop recommendations concerning effective physical activity policies and programs to address obesity in children. The conference was attended by approximately 1,000 delegates from 33 countries who gathered to listen to the invited speakers and to share information on promising practices related to the promotion of physical activity with the aim of reducing the burden of obesity in children. The major topics addressed at the conference included the biological and behavioural causes of obesity, current and past levels of physical activity and sedentarism in children, the role of the social, family, and built environments in addressing the physical activity deficit, and the role of legislation and industry in promoting physical activity. Promising physical activity interventions among children were presented, and important research, policy, and practice recommendations to address the issue of physical inactivity and obesity were provided.