Violence is a leading cause of morbidity and mortality for youth, with more than 600,000 emergency department visits annually for assault-related injuries. Risk for criminal justice involvement among this population is poorly understood. The objective of this study was to characterize arrests among high-risk, assault-injured, drug-using youth following emergency department treatment. Youth (aged 18-24 years) with past 6-month drug use who were seeking emergency department treatment for either an assault or for non-violence reasons were enrolled (December 2009-September 2011) in a 2-year longitudinal study. Arrests in the 24 months following the emergency department visit were analyzed in 2016-2017 using survival analysis of objective Law Enforcement Information Network data. Hazard ratios quantifying the association between risk factors for arrest were estimated using Cox regression. In the longitudinal cohort, 511 youth seeking emergency department care (assault injury group n=299, comparison group n=212) were aged ≥18 years and were included for analysis. Youth in the assault injury group cohort had a 47% higher risk of arrest than the comparison group (38.1% vs 25.9%, RR=1.47, p<0.05). In unadjusted analyses, male sex, assault injury, binge drinking, drug use disorder, and community violence exposure were all associated with increased risk of arrest during the follow-up period. Cox regression identified that male sex (hazard ratio=2.57), drug use disorder diagnosis (hazard ratio=1.42), assault injury at baseline (hazard ratio=1.63), and community violence exposure (hazard ratio=1.35) increased risk for arrest. Drug-using assault-injured youth have high rates of arrest. Emergency department and community interventions addressing substance use and violence involvement may aid in decreasing negative violence and criminal justice outcomes among high-risk youth. This study is registered at www.clinicaltrials.gov NCT01152970.