This K23 Mentored Patient-Oriented Research award proposal is designed to provide the scholarly training, mentorship, and support necessary for the candidate to develop into an independent clinical investigator focused on child obesity prevention and treatment in community settings. The candidate's long-term objective is to improve the effectiveness of intervention programs for child overweight prevention and treatment, particularly community programs for underserved populations. To achieve this objective, the candidate will pursue didactic and experiential training in three specific areas: 1) qualitative research techniques to examine the needs, preferences, and participation motivations and barriers among potential intervention participants and stakeholders, 2) application of health promotion behavior change models and prevention science and use of community-based participatory research (CBPR) principles, and 3) analytic skills for the design, implementation, and assessment of community-based intervention trials. The candidate has identified two co-sponsors with complementary expertise in behavioral therapy for child overweight treatment and adherence to care in chronic disease to provide mentorship during the five-year training plan. Additional mentoring will be provided by consultants with expertise in qualitative methods and community-based research. The three inter-related studies proposed build on the training objectives and will each contribute to an improved understanding of effective approaches to help overweight children and parents adopt and sustain healthy behaviors. The specific aims are: 1) to understand primary motivations and barriers to participation and retention and to determine stakeholder recommendations for enhanced efficacy and sustainability of an existing community-based health promotion program (Strong Kids) for overweight children using the Integrative Theory of Behavior, 2) to use data gathered in Aim 1 along with published evidence regarding weight-related behavior change in a collaborative research process with community stakeholders to systematically enhance Strong Kids and to test the feasibility of training YMCA coaches in the enhanced intervention, and 3) to conduct a controlled intervention trial in collaboration with the community partners that measures change in weight-related behavior and health outcomes in an enhanced Strong Kids program compared to a wait-list control. After obtaining the training, experience and skills through this K23 Award, the candidate will be prepared to design, obtain funding for, and to conduct a large-scale trial of a community-based healthy lifestyle intervention for overweight children.