Josine Junger-Tas introduced the Communities That Care (CTC) prevention system to the Netherlands as a promising approach to address the growing youth violence and delinquency. Using data from a randomized trial of CTC in the United States and a quasi-experimental study of CTC in the Netherlands, this article describes the results of a comparison of the implementation of CTC in 12 U.S. communities and five Dutch neighborhoods. CTC communities in both countries achieved higher stages of a science-based approach to prevention than control communities, but full implementation of CTC in the Netherlands was hampered by the very small list of prevention programs tested and found effective in the Dutch context.