Examples of the impact that contextual fit can have on implementation are available in every discipline. Consider one intervention focused on reducing substance abuse developed in the Midwest that emphasized both the development of after-school community activities and family support. The intervention had been used with significant success in two midwestern states and was highly anticipated by community organizers in an urban west coast context. The intervention manual and materials were purchased; midwestern developers were hired to assist with implementation; and a series of community events, training forums for mental health professionals, and orientations for youth and families were funded. Unfortunately, there was no effort to assess whether the roles, responsibilities, and specific strategies of the intervention were valued by and culturally comfortable with the families, youth, or local professionals. Insufficient attention was paid to language differences and parents’ expectations. The poor match between the vision that parents in the host city had for themselves and the expectations of the intervention led to both poor-quality implementation and no change in substance abuse levels. The same intervention implemented two years later in a southwestern urban setting was launched only after adapting the intervention to fit the local culture. Core features of the intervention were retained, but the process of introduction (presentations by local leaders, not external leaders) was modified to launch the program from within the community rather than as an external “initiative.” Recasting materials to fit local language and cultural norms combined with a strong emphasis on training by local community members rather than external experts enhanced the contextual fit of the intervention for that specific location. The result was higher implementation fidelity and valued improvement in reported rates of substance abuse by youth.