Among adolescents (ages 12-17) and young adults (ages 18-25) enrolled in Medicaid or the Children's Health Insurance Program (CHIP), 0.5% of adolescents had opioid use disorder (OUD), 3.0% had other risky opioid use, 3.4% had another substance use disorder, and 21.6% used other substances without disorder. Compared to adolescents, the prevalence of OUD and other risky opioid use was about 3 and 2 times higher among young adult enrollees, among whom 1.6% had OUD and 5.8% had other risky opioid use. Among young adults, 8.6% had another SUD and 61.8% used other substances without disorder. Prevalence of OUD or other risky opioid use was substantially higher among Medicaid-enrolled youth with other substance use or health risk factors including more than double among those with fair or poor health, more than 3 times higher among those with heavy alcohol use, and more than 1.5 times higher among those with a major depressive episode. Results underscore the need to take a whole person approach to addressing risks for OUD.