The COVID-19 pandemic has forced colleges and universities in the United States to make decisions about how to best protect students and employees from the virus. In this article, we investigate the factors that lead to human resources decisions to mandate vaccines among students and employees. We draw heavily on the crisis management literature and the neo-institutional theory of isomorphism to investigate the ways in which coercive, mimetic, and normative pressures relate to institutional behaviors. Our findings suggest that coercive pressures may influence an institution's decision to require vaccines for students and employees. State bans against vaccine mandates are negatively correlated with the implementation of a vaccine mandate for students. Mimetic isomorphism may also be a strong influence on an institution's decision to require vaccines for students and employees. Regression models indicate that an institution is more likely to require vaccines for students and staff if their peer institutions also require vaccines.