Public policy in the United States has historically considered youth violence as a moral problem to be punished after the fact, but growing scientific evidence supports a public health perspective on violent behavior as an interaction between cultural forces and failures in development. Prevention science has provided a bridge between an understanding of how chronic violence develops and how prevention programs can interrupt that development. Articles in this journal supplement provide yet another bridge between efficacious university-based programs and effective community-based programs. It is suggested that yet one more bridge will need to be constructed in future research between community-based programs that are known to be effective and community-wide implementation of prevention efforts at full scale. This last bridge integrates the science of children's development, the science of prevention, and the science of public policy.