We describe critical participatory principles and practices used in a successful multiyear partnership between university researchers and a public elementary school district to implement an efficacy trial of the Puentes program, a family-based program to prevent school disengagement and mental health problems in Mexican origin seventh graders. We highlight the role of the School Advisory Board (SAB) as the principle structure facilitating the collaboration and the expansion of roles and power sharing that evolved over the course of the project. We also present the results of a focus group conducted to evaluate the school district’s perspective on the partnership. We end by sharing conclusions regarding the critical aspects of the partnership. Editors’ Strategic Implications: Researchers and educators alike will benefit from the lessons on how to work together toward effective and sustainable prevention programming.