In the United States, firearms are involved in tens of thousands of deaths and injuries each year. The magnitude of this problem prompted the National Academy of Sciences (NAS) to issue a report in 2004 detailing the strengths and limitations of existing research on the relationship between firearms and violence. In response, a multidisciplinary group of experts in the field of firearms and violence formed the National Research Collaborative on Firearm Violence. The Collaborative met for 2 days in June 2005 to (1) critically review the main findings of the NAS report and (2) define a research agenda that could fill research and data gaps and inform policy that reduces gun-related crime, deaths and injuries. This article summarizes the Collaborative's conclusions and identifies priorities for research and funding.