Purpose: Concerns about violence stemming from the use of firearms and other illegal weapons among youth is well-founded. However, relatively little is known about what drives some youth to carry weapons and not others. It is hypothesized that weapon carrying is a response to threat posed by prior victimization and traumatic experiences even while controlling for demographic characteristics and mental health status. Methods: Structured face-to-face interviews of 723 residential youth (M age = 15.5, SD = 1.23; 87% male) in all 32 Missouri Division of Youth Services facilities were conducted. Measures of weapon carrying frequency, demographic characteristics, and mental health symptoms and status were employed. Predictive measures included the Massachusetts Youth Screening Instrument-Second Version (MAYSI-2) ( = .77 for females and .68 for males) and a four-item index of prior victimization ( = .76). Ordinary Least Squares (OLS) regression was used to assess the relationship of trauma and prior victimization on the frequency of weapon carrying. Results: Descriptive findings reveal that weapon carrying was extensive in the study population. A total of 37.1% of the study reported carrying a hidden weapon everyday prior to commitment with males (42.1%) more likely than females (22.0%) to carry. A greater proportion of Latinos/Latinas (57.1%) and African-Americans reported carrying a weapon everyday compared to Whites (28.8%). Although a greater percentage of urban youth reported carrying a hidden weapon (51.2%), Small town (30.0%) and suburban (29.0%) youth carried weapons at high rates. Linear regression models revealed that prior trauma and victimization possessed incremental validity in predicting weapon carrying (DRē = .101, p <.001) accounting for 10.1% explained variance over and above demographic and mental health disorders and symptoms. Further, item-level analyses showed that having been attacked by someone with a weapon and having ever seen someone severely injured or killed in person were the primary predictors driving the results. Implications for policy: This study adds important new evidence about the multidimensional impacts of victimization and trauma on the epidemic of weapon carrying among youth. It also provides clear social policy implications in that strategies capable of ameliorating trauma and exposure to violence would in turn interrupt the cycle of violence via the mechanism of weapon carrying reduction.