Highly conscientious workers are more motivated and productive than their less conscientious colleagues. Moreover, conscientious employees tend to be more satisfied and less stressed from their work. One consequence of the COVID-19 pandemic, however, is that many workers have transitioned to working remotely, often under conditions of less direct supervision and less clarity about expected work activities and outcomes. We proposed that this significant change in work context constitutes a weakening of situational strength that can change the relationship of conscientiousness with job strain, job satisfaction, and job performance. Using Meyer et al.’s (2010) conceptualization of situational strength, we tested the moderating effect of situational strength by surveying 474 white-collar employees in a Fortune-1000 firm in 2019 and again in 2020 after they had all transitioned to working remotely. We found that the changes in work context due to COVID-19 significantly lowered scores on situational strength and this was accompanied by a stronger positive effect of conscientiousness on performance. Importantly, during COVID-19, the relationships of conscientiousness with strain and satisfaction showed a reversal of sign, with more conscientious workers reporting higher strain and lower satisfaction. These effects were partially mediated by job demands and were replicated with work hours. The results provide a test of situational strength theory and suggest that changes in situational strength due to COVID-19 may cause an organization’s most conscientious employees to be at elevated risk for burnout and dissatisfaction, and consequently, turnover, if not managed appropriately. (PsycInfo Database Record (c) 2021 APA, all rights reserved)