Although alliances between community-based organizations (CBOs) and university-based evaluators provide opportunities to enhance community-based interventions, such partnerships may be fraught with challenges and obstacles. This paper focuses on the "story" behind a collaborative partnership between a Latino-focused CBO and a team of university-based evaluators that was formed to evaluate HIV prevention interventions for Mexican American female adolescents and gay/bisexual/questioning (GBQ) Latino male adolescents. A developmental trajectory of the partnership is detailed, with a focus on the creation and enhancement of a reciprocal and mutually beneficial relationship. In tracing this history, the paper explores challenges that were faced and presents ways in which the partnership attempted to overcome obstacles. Recommendations are offered to assist in the formation and maintenance of collaborative partnerships between CBOs and university-based evaluators/researchers.