This study reports on the development of a comprehensive assessment of exposure to guns and gun-related violence for evaluating the risk of gun-related trauma. Gun access, gun attitudes, gun safety education, and exposure to gun violence were measured. Participants were 630 youth, aged 2-17. Youth, ages 10-17, completed a self-report survey and caregivers of young children, ages 2-9, completed the survey as a proxy for that child. The youth were from urban (n = 286) and rural (n = 344) areas. Factor analysis, item response theory, and structural equation modeling were used. Two factors described access to guns, two factors described gun attitudes, and a single construct captured gun safety education. The gun violence exposure factor showed strong associations with trauma symptomatology. The individual constructs showed good psychometric properties and measurement noninvariance by urbanicity.