The Behavioral Change Consortium (BCC) Nutrition Workgroup (NWG) is a multidisciplinary collaboration of representatives from BCC sites and federal agencies. Its mission is to improve measurement of dietary variables. This article presents findings from a qualitative study of perceived effectiveness of the workgroup collaboration. Twelve in-depth interviews were conducted and examined for common themes using the constant comparison method. Themes contributing to perceived effectiveness included: funding and additional resources; invested, committed, and collegial members; strong leadership, clearly articulated goals, and regular communication. Influences seen as reducing effectiveness were: distance, disparate nature of the studies, limited time, and problems associated with starting collaboration after the primary studies had begun data collection. NWG members felt that the workgroup would continue to be successful; however, there were concerns about responsibility for writing and authorship of manuscripts and the need for continued funding to ensure full participation and productivity.