How does the public form opinions for countries’ use of drones? To the extent scholars explore this question, they focus on public attitudes in terms of approval and support. Though scholars, policy-makers, and practitioners acknowledge that legitimacy, defined as the public’s subjective beliefs in the appropriateness of behavior, is central to the sustainability of drone policies, few—if any—experts investigate this outcome empirically. This creates the potential for biased judgments regarding public perceptions of legitimate strikes. In this study, I research how the public understands the legitimacy of drone strikes. I elucidate and empirically evaluate mechanisms relating to countries’ variation in their use and constraint of drones that I hypothesize can shape the public’s perceptions of legitimacy in a U.S. domestic and cross-national context. To gain leverage over perceptions of legitimacy in these settings, I use a mixed-methods research design consisting of structured, focused case studies and original survey experiments. I find that though drone warfare can be conceived as a leader-driven practice, with especially U.S. presidents given wide latitude to use strikes based on their positional authority that may allow them to manipulate public opinion, variation in why and how drones are used can moderate Americans’ perceptions of legitimate strikes. I also find that this effect is generalizable to France. Similar to the United States, France is the only other great power that currently uses drones beyond its borders and region. Overall, then, the results show that legitimacy can be a useful dependent variable for researchers attempting to gauge the public’s understanding of appropriate drone use. My findings also show that perceptions of legitimacy may or may not relate to the expectations of leaders, and that the differences can be due to shifts in why and how strikes are used and constrained.