Homeless youth generally have significantly higher rates of risky sexual activity, substance use, and depressed mood compared to their non-homeless peers. Sexual minority youth are over-represented in the homeless youth population compared to their numbers in the general population, comprising 20-40% of homeless youth, and most studies have found higher rates of risky sexual behaviors, use of substances, and depressed mood among homeless sexual minority youth compared to homeless heterosexual youth, likely due to issues of discrimination and marginalization stemming from their sexual minority status. f homeless heterosexual and sexual minority youth, who are simultaneously receiving health services over the same time period, can lead to a better understanding of and improved interventions for, these youth. Homelessness may be a more critical factor for these youth engaging in risky behaviors, and having poor mood, than sexual orientation per se. Sexual Behaviors, Substance Use, and Mood in a Cohort of Homeless Youth: Comparisons between Homeless Heterosexual and Sexual Minority Youth Seth Ammerman