Source: (2005) Canadian Journal of Criminology and Criminal Justice/Revue canadienne de criminologie et de justice penale. April/avril: 337-354.In an evidence-based society, government crime prevention policy and local practice would be based on interventions with demonstrated effectiveness in preventing crime - using what works best. Systematic reviews are the most comprehensive method of assessing the effectiveness of crime prevention measures and, in an evidence-based society, they would be the source that governments would turn to for help in the development of policy. This article summarizes the main findings of a project of the Campbell Collaboration Crime and Justice Group to advance knowledge on what works to prevent crime for a wide range of interventions, organized around four important domains: at-risk children, offenders, victims, and high-crime places. The full conclusions are published in the forthcoming book, Preventing Crime: What Works for Children, Offenders, Victims, and Places. The good news from this first wave of reviews is that most of the interventions are effective in preventing crime and, in many cases, produce sizeable effects. This includes social-skills training for children, cognitive-behavioural therapy and incarceration- based drug treatment for offenders, face-to-face restorative justice conferences involving victims and offenders, prevention of repeat residential burglary victimization, hot spots policing, closed-circuit television surveillance, and improved street lighting. Acting on the evidence from these systematic reviews could contribute to a safer society, both now and in the long run. Alongside the Campbell Collaboration effort to prepare and maintain systematic reviews for use by policy makers, practitioners, and the general public, a program of research into new crime prevention and intervention experiments needs to be initiated. Author's abstract.