Gun Buyback programs have been implemented in various forms in countries such as the UK, USA, Brazil, Australia, and Argentina. Whether or not these programs are an effective approach for reducing national violent crime and homicides, however, remains unclear. Much of the uncertainty is due to the different ways in which Gun Buyback programs have been implemented. The Australian Gun Buyback program is distinguished from Gun Buyback programs in other countries by its abrupt implementation, its narrow focus on a particular class of firearms, and its broad application across the entire population. We assess the impact of Australia’s 1996 Gun Buyback program on national homicide rates using a synthetic control group quasi-experimental design, comparing the results to suicide and motor vehicle fatality trends to test for plausible alternative hypotheses. Results suggest that the Gun Buyback program significantly reduced Australia’s homicide rate in the decade following the intervention (1997–2007).