Firearm violence causes significant public health burden, but there is a lack of research concerning motivations for firearm access despite clear epidemiological risk. Developing robust tools to measure attitudes toward firearms and firearm-related behaviors can improve our ability to conduct firearm violence research. We aimed to develop a feasible and effective tool that could indirectly measure firearm beliefs. A total of 274 undergraduates were recruited from two southern universities and completed an implicit association test (IAT) designed to indirectly assess attitudes toward firearms (Firearm IAT). Participants also completed self-report measures, including Attitude Toward Guns Scale (ATGS) and Gun Beliefs and Behavior Scale (GBBS) to examine explicit attitudes toward firearms. Demographic and firearm-related data were also assessed. The Firearm IAT revealed an association between firearms and negatively valenced words. The Firearm IAT had a good internal consistency and construct validity with a D score that is significantly different from 0 and a reliability score of 0.84. The Firearm IAT showed significant positive correlations with ATGS and GBBS suggesting this measure could serve as an indirect assessment of firearm attitudes.