Applied Prevention Science International (APSI) was formed to assist national and international policy makers and practitioners to apply prevention science to address substance use and other related issues within their communities. Working in collaboration with international organizations, APSI provides advice, consultation, and services to support the interface among science, policy, and practice, including project development and coordination; science-based training and certification of prevention professionals; and evaluation and research efforts in substance use. The overall purpose is to assist in the development of trained prevention professionals who can implement the most effective and science-proven prevention interventions and policies.