In the complex modern world, people's understanding of how things work is often outsourced to other people. We explore how people's perceptions of expert causal understanding of the coronavirus disease (COVID-19) pandemic predicted their pandemic-related behaviors. As part of a larger longitudinal study, we collected data at four time points that measured participants' perceptions of experts' causal understanding of COVID-19, along with those participants' self-reported pandemic-related health behaviors. We found that perceiving experts to understand the causal mechanism of transmission was predictive of engaging in more social distancing, advice following, hand washing, and mask wearing. Believing experts could intervene and treat the symptoms or underlying cause of COVID-19 was negatively associated with these same behaviors, but to a lesser degree. These results held above and beyond political ideology and were overall similar for people who perceived themselves to be at high or low risk for COVID-19. This research provides new insights into how people's behaviors are guided by perceptions of others' understanding and highlights important implications for expert health-risk communication. (PsycInfo Database Record (c) 2022 APA, all rights reserved).