Although firearm homicide remains a topic of interest within criminological and policy discourse, existing research does not generally undertake longitudinal comparisons between countries. However, cross-country comparisons provide insight into whether "local" trends (e.g., declines in firearm homicide in one particular country) differ from broader, international trends. This in turn can improve knowledge about the role of factors such as policing practices and socioeconomic variables in the incidence of lethal violence using firearms. The current study compares long-term firearm homicide trends in three countries with similar social histories but different legislative regimes: Australia, Canada, and New Zealand. Using negative binomial regression, the study found that the most pronounced decline in firearm homicide over the past two decades occurred in New Zealand. Connections between social disadvantage, policing policy, and violence are discussed. (Contains 2 notes, 1 table, and 1 figure.)