Over the past decade researchers have identified intervention strategies and program models that reduce delinquency and promote pro-social development. Preventing delinquency, says Peter Greenwood, not only saves young lives from being wasted, but also prevents the onset of adult criminal careers and thus reduces the burden of crime on its victims and on society. It costs states billions of dollars a year to arrest, prosecute, incarcerate, and treat juvenile offenders. Investing in successful delinquency-prevention programs can save taxpayers seven to ten dollars for every dollar invested, primarily in the form of reduced spending on prisons. According to Greenwood, researchers have identified a dozen "proven" delinquency-prevention programs. Another twenty to thirty "promising" programs are still being tested. In his article, Greenwood reviews the methods used to identify the best programs, explains how program success is measured, provides an overview of programs that work, and offers guidance on how jurisdictions can shift toward more evidence-based practices The most successful programs are those that prevent youth from engaging in delinquent behaviors in the first place. Greenwood specifically cites home-visiting programs that target pregnant teens and their at-risk infants and preschool education for at-risk children that includes home visits or work with parents. Successful school-based programs can prevent drug use, delinquency, anti-social behavior, and early school drop-out. Greenwood also discusses community-based programs that can divert first-time offenders from further encounters with the justice system. The most successful community programs emphasize family interactions and provide skills to the adults who supervise and train the child. Progress in implementing effective programs, says Greenwood, is slow. Although more than ten years of solid evidence is now available on evidence-based programs, only about 5 percent of youth who should be eligible participate in these programs. A few states such as Florida, Pennsylvania, and Washington have begun implementing evidence-based programs. The challenge is to push these reforms into the mainstream of juvenile justice.