• Most mental health symptoms examined were unrelated to gun violence.
• Hostility predicted threatening someone with a gun.
• Impulsivity predicted gun carriage.
• Gun access strongly predicted gun violence even after controlling for mental health.
Despite the public, political, and media narrative that mental health is at the root of gun violence, evidence is lacking to infer a causal link. This study examines the temporal associations between gun violence (i.e., threatening someone with a gun and gun carrying) and mental health (i.e., anxiety, depression, stress, PTSD, hostility, impulsivity, and borderline personality disorder) as well the cross-sectional associations with gun access and gun ownership in a group of emerging adults. Waves 6 (2015) and 8 (2017) data were used from a longitudinal study in Texas, US. Participants were 663 emerging adults (61.7% female) including 33.6% self-identified Hispanics, 26.0% white, 27.0% Black, and 13.4% other, with an average age of 22 years. Multivariate logistic regression indicated that, individuals who had gun access were 18.15 times and individuals with high hostility were 3.51 times more likely to have threatened someone with a gun, after controlling for demographic factors and prior mental health treatment. Individuals who had gun access were 4.74 times, individuals who reported gun ownership were 5.22 times, and individuals with high impulsivity were 1.91 times more likely to have carried a gun outside of their homes, after controlling for prior gun carrying, mental health treatment, and demographic factors. Counter to public beliefs, the majority of mental health symptoms examined were not related to gun violence. Instead, access to firearms was the primary culprit. The findings have important implications for gun control policy efforts.