The field of delinquency prevention has been transformed in recent years with the advent and expansion of evidence-based practice. We first depict the risk-focused prevention perspective, which is based on the empirical identification of risk factors that predict delinquency behavior. Evidence-based practice in delinquency prevention is then described, followed by the associated consideration of what makes for successful implementation of prevention programs—this is referred to as “implementation fidelity.” Lastly, three model programs are described that illustrate evidence-based practice in delinquency prevention. The notion of “best practices” is extremely popular these days, but true best practices are substantiated by evaluation research that gages effectiveness, as provided in evidence-based practice.