This analysis of the Youth Risk Behavior Survey examined HIV syndemic factor associations (substance use, violence, mental health, and HIV risk behaviors) among adolescent gay, bisexual, and other men who have sex with men—a population with the highest prevalence of undiagnosed HIV infections. The representative sample (n = 644) exhibited low condom use (52%) and HIV testing (21%). Adjusted multivariate logistic regression models showed that Blacks were less likely to report HIV testing (adjusted odds ratio [aOR] = 0.06, 95% confidence interval [CI] [0.01–0.44], p < .01), whereas Hispanics were more likely to report four or more lifetime sexual partners (aOR = 3.75, 95% CI [1.49–9.44], p < .01), compared with Whites. A syndemic of substance use and intimate partner violence (sexual, sexual dating, and/or physical dating violence) was associated with early intercourse, multiple sexual partners, and drugs/alcohol before intercourse. Multiple syndemic factor exposures were associated with additive risk, suggesting multilevel approaches for HIV prevention.