The coronavirus disease 2019 (COVID-19) poses a serious global health threat. Without a vaccine, behavior change is the most effective means of reducing disease transmission. Identifying psychological factors that may encourage engagement in preventative health behaviors is crucial. The behavioral immune system (BIS) represents a set of psychological processes thought to promote health by encouraging disease avoidance behaviors. This study examined whether individual differences in BIS reactivity (germ aversion, pathogen disgust sensitivity) were associated with concern about COVID-19 and engagement in recommended preventative health behaviors (social distancing, handwashing, cleaning/disinfecting, avoiding touching face, wearing facemasks). From March 20 to 23, 2020, a US national sample (N = 1019) completed an online survey. Germ aversion and pathogen disgust sensitivity were the two variables most consistently associated with COVID-19 concern and preventative health behaviors, while accounting for demographic, health, and psychosocial covariates. Findings have implications for the development of interventions intended to increase preventative health behaviors.