Twelve City of Chicago agencies led by the Chicago Department of Public Health (CDPH) have utilized an Inter-departmental Task Force on Childhood Obesity (IDTF) to reduce the prevalence of childhood obesity in Chicago. A participatory evaluation of the task force was used to create an Integrated Visual Logic Model (IVLM) showing the task force structure and the added value it provides. This visual mapping of task force efforts helps articulate the IDTF’s current functioning. Data contributing to the IVLM includes recommendations from agency staff/task force members about meeting functioning, planning, community outreach, education and programming. Archival data analysis, systematic observations, and key informant interviews suggest that synergy — defined here as the added value derived from active participation and engagement, leading to greater efficiency and innovation—is central to the task force’s effectiveness. The evaluation has led to efforts currently underway to use the IVLM for goal setting and planning.