This report discusses the principles for effective delinquency prevention and early intervention, the risk and protective factors, the systems responsible for implementing delinquency prevention, and what works in delinquency prevention. Prevention strategies at various child and juvenile developmental stages are also addressed. The report notes that in recent years, new prevention strategies have emerged to focus on stopping offending behavior before it begins by targeting conditions and factors that may cause individuals to engage in criminal and violent behaviors. These community strategies mobilize law enforcement, justice agencies, business and community leaders, schools, and health and social service agencies to develop coordinated solutions to stop violence before it starts. Another principal feature of these new endeavors, in addition to collaboration, is their growing reliance on a critical mass of research and evaluation findings. Through these evaluations, communities can identify programs that have proven effective or promising in reducing risk factors associated with delinquent and criminal careers, as well as programs that enhance protective factors that contribute to more resilient youth. Prevention programs established under the Crime Act are also listed. 28 references and appended program descriptions