Considering the challenges inherent to collaboration and the time it takes to achieve measurable outcomes, partnerships need a way to determine, at an early stage, whether they are making the most of collaboration. The authors have developed a new measure, partnership synergy, which assesses the degree to which a partnership's collaborative process successfully combines its participants' perspectives, knowledge, and skills. This article reports the results of a national study designed to examine the relationship between partnership synergy and six dimensions of partnership functioning: leadership, administration and management, partnership efficiency, nonfinancial resources, partner involvement challenges, and community-related challenges. Data were collected from 815 informants in 63 partnerships. Results of regression analysis conducted with partnership-level data indicated that partnership synergy was most closely related to leadership effectiveness and partnership efficiency. Implications of these findings for research and practice are discussed.