Given the heightened risk for HIV and other STIs among young men who have sex with men (YMSM) as well as the racial/ethnic disparities in HIV/STI risk, an understanding of longitudinal trends in sexual behaviors is warranted as YMSM emerge into adulthood. Drawing from an ongoing prospective cohort study, the present analysis employed latent growth curve modeling to examine trends in distinct types of sexual activity without condoms over time in sample of YMSM and examine differences by race/ethnicity and perceived familial socioeconomic status (SES). Overall, White and Mixed race YMSM reported more instances of oral sex without condoms as compared to other racial/ethnic groups with rates of decline over time noted in Black YMSM. White YMSM also reported more receptive and insertive anal sex acts without a condom than Black YMSM. Declines over time in both types of anal sex acts without condoms among Black men were noted when compared to White men, while increases over time were noted for mixed race YMSM for condomless insertive anal sex. The effects for race/ethnicity were attenuated with the inclusion of perceived familial SES in these models. These findings build on previous cross sectional studies showing less frequent sex without condoms among Black YMSM despite higher rates of HIV incidence in emerging adulthood, as well as the importance of considering economic conditions in such models. Efforts to understand racial/ethnic disparities in HIV/STIs among YMSM must move beyond examination of individual-level sexual behaviors and consider both race/ethnicity and socioeconomic conditions in order to evaluate how these factors shape the sexual behaviors of YMSM.