This AEA 2013 panel from Harder+Company Community Research, First 5 San Diego, and the American Academy of Pediatrics highlights key Community Based Participatory Research (CBPR) elements that contributed to a highly collaborative relationship among an evaluator, funder, and program staff to evaluate a large, complex system of care for young children and their families. First 5 Commission of San Diego County provides developmental and behavioral services for children with mild to moderate needs via 19 community agencies, including hospitals, a state university, a community health center, and community-based nonprofits. Through the lens of CBPR, panelists will describe the importance of evaluating the developmental gains made by children in this system and measuring overall program effectiveness. By incorporating the interests of all partners, this intensive approach promoted programmatic and system changes to improve children's health. Presenters will also describe how the project partners continually refine the evaluation plan, measurement protocols, and data reporting requirements to ensure the evaluation represents the needs of the community and demonstrates the impact of services. #Collaborative,ParticipatoryandEmpowermentEval #2013Conference