Understanding the Impacts of Research Synthesis

•Synthesis research is gaining prominence in the science policy landscape.•There has been little empirical examination of the impacts of these initiatives on policy and practice.•This paper reviews 10 case studies from within biodiversity conservation and natural resource management from around the world.•A novel conceptual framework is used to assess the impacts of, and assumptions underpinning the research synthesis.•Findings suggest that research synthesis is having various types of impacts on policy and practice.