Purpose To test whether the impact of subjective norms, race/ethnicity-specific descriptive norms, vaccine conspiracy beliefs, and prosocial concern on COVID-19 vaccination intentions differs by race/ethnicity for young adults. Design Cross-sectional study. Setting May-August 2021 in Texas. Subjects Racially/ethnically diverse unvaccinated college students (N = 314). Measures COVID-19 vaccination intentions, theory-driven constructs (eg, perceived susceptibility), vaccine conspiracy beliefs, prosocial concern, and social norms. Analysis Block-sequential multiple Tobit regression. Results Results revealed three significant two-way interactions between race/ethnicity and (1) subjective norms, F (5, 251) = 2.28, P < .05; (2) COVID-19 vaccine conspiracy beliefs, F (5, 251) = 2.88, P < .05; and (3) prosocial concern, F (5, 251) = 2.61, P < .05. There was a positive association between subjective norms and intentions for European and African Americans, a positive association between prosocial concerns and intentions for European and multiracial/multiethnic Americans, and a negative association between conspiracy beliefs and intention for Hispanics. The interaction between race/ethnicity and race/ethnicity-specific descriptive norms was not significant, F (5, 251) = 1.09, P = .37. Conclusion Although based on a relatively small sample, our findings suggest the importance of culturally tailoring COVID-19 vaccination messages to correct conspiracy beliefs, signaling a positive subjective norm, and enhancing prosocial concerns for specific racial-ethnic groups.