ParticipACTION: the future challenges for physical activity promotion in Canada.

This commentary is the concluding piece of a series of papers about the Canadian ParticipACTION initiative. It describes the resurgence of the new ParticipACTION as a national communications initiative in Canada, and sets this in an international context. The set of ParticipACTION papers in this issue establish benchmarks and provide baseline and initial impact data for the evaluation and monitoring of ParticipACTION, using qualitative and quantiative research methods. As a set, they describe a comprehensive approach to setting up evaluations of national social marketing efforts to promote physical activity.