Fostering Healthy Futures (FHF) is a randomized, controlled trial of an innovative preventive intervention for preadolescent youth (ages 9-11) placed in out-of-home care. The program is designed to promote child well-being by identifying and addressing mental health issues, preventing adolescent risk behaviors, and promoting competence. This paper describes the design, implementation, and uptake of the FHF program as well as our approaches to the challenges of conducting research-based prevention work within a child welfare setting. (Contains 1 figure.)