Tomczyk Samuel In Programme October, 23 10:50 to 12:20 October, 23 15:00 to 16:30 Hours & Dates Wednesday, October 23 10:50 Mechanisms and outcomes in substance use prevention among youth10:50 to 12:20Room 5AOral presentation session Wednesday, October 23 15:00 Keynote presentation Evidence-based prevention through collaborative action? Opportunities and challenges for community-based participatory research in prevention science 15:00 to 16:30 Auditorium I Samuel Tomczyk