OBJECTIVE: Understanding compliance with COVID-19 mitigation recommendations is critical for informing efforts to contain future infectious disease outbreaks. This study tested the hypothesis that higher levels of worry about COVID-19 illness among household caregivers would predict lower (a) levels of overall and discretionary social exposure activities and (b) rates of household SARS-CoV-2 infections. METHODS: Data were drawn from a surveillance study of households with children ( RESULTS: Caregivers with high enrollment levels of worry about COVID-19 illness were more likely to reduce direct social contact outside the household, particularly during the U.S.'s most deadly pandemic wave. Households of caregivers with lower COVID-19 worry had higher odds of (a) reporting discretionary outside-the-home social interaction and (b) SARS-CoV-2 infection. CONCLUSIONS: This was, to our knowledge, the first study showing that caregiver COVID-19 illness worry was predictive of both COVID-19 mitigation compliance and laboratory-determined household infection. Findings should inform studies weighing the adaptive value of worrying about infectious disease outbreaks against established detrimental health effects.