This chapter discusses the development and evolution of a school‐based primary prevention program and associated evaluations funded by the US Department of Justice (DOJ). The Gang Resistance Education and Training (G.R.E.A.T.) program evolved from a local Phoenix program to one that was exported initially to urban areas but eventually to suburban and rural communities as well as to tribal locales and military bases overseas. As the G.R.E.A.T. program spread across the United States, an immediate concern was to ensure the fidelity of the program as it was adopted by other agencies. The program goals target individual outcomes and, as such, individual adolescents are the intended audience. By 2004, the “new and improved” G.R.E.A.T. program was in full operation. The revised program includes the same goals as the original G.R.E.A.T. as well as a third specific goal: assist youths to develop positive relationships with law enforcement.