We report four studies (N = 1419) which examined people’s emotional reactions from March to April 2020 when the COVID-19 crisis was unfolding rapidly with exponentially increasing rates of infections and fatalities. Specifically, we examined how emotions influenced the endorsement of virus-prevention behaviors that may contribute to slowing the spread of COVID-19, as well as eudaimonic functioning during the crisis. Study 1A and 1B provided naturalistic evidence that mixed emotions predicted endorsements of legitimate virus-prevention behaviors and eudaimonic functioning in both the United States and Singapore. Study 2 replicated Study 1 and provided evidence for receptivity as a mediator between mixed emotions and these outcomes. Finally, Study 3 provided experimental evidence that mixed emotions causally increased endorsements of legitimate virus-prevention behaviors and eudaimonic functioning. Across all studies, positive and negative emotions were unrelated to legitimate virus-prevention behaviors, while relationships with eudaimonic functioning were inconsistent. Theoretical and practical implications are discussed.