Adolescents involved with the juvenile justice system have higher rates of risky sexual behaviors, resulting in high rates of sexually transmitted infections and increased risk of human immunodeficiency virus, early or complicated pregnancy, and parenting issues. Comorbid substance abuse, gang association, mental health issues, and history of having been abused as children result in further elevated rates. Girls and lesbian, gay, bisexual, and transgender youths represent growing subpopulations with special risks. Increasingly diverted to community-based alternatives, juvenile justice-involved teens obtain most of their medical care from community providers, who need to understand their risks to provide appropriate, optimal care.