One in five new HIV diagnoses in the United States is among persons younger than 25 years old. Routine testing is a crucial prevention strategy. We assessed the relationships between sex, race, sexual orientation, and HIV testing among young adults. Odds of affirmative testing history were higher among women than men, and among Latino gay/bisexual men than their White counterparts. Among straight men, odds of having tested were greatest among Blacks. Mechanisms through which race/ ethnicity affect HIV vulnerability among young gay/bisexual men of color need to be explored, especially as these populations are more likely to have affirmative testing histories, yet are disproportionately impacted.