The COVID-19 pandemic is a global public health crisis which has resulted in high rates of excess deaths and widespread maladaptive social, economic, and health outcomes. Although the unprecedented development and roll-out of vaccines has shown promise in booting immunity and reducing the burden of mortality, the rise of new variants of concern, particularly the highly contagious B.1.617.2 (Delta) variant, has resulted in new waves of infections and continued maladaptive outcomes. Restrictions on movement and gatherings, and advocacy or mandating of mitigation behaviors like social distancing and wearing face coverings, remain in many countries and districts worldwide. Reports of poor mental health, economic hardship, ‘lockdown’ fatigue, laxity in following mitigation guidelines, vaccine hesitancy, and hoarding behavior has presented governments and public health authorities with considerable challenges to maintain mitigation behaviors and reduce maladaptive outcomes on increasingly exasperated and weary populations. Social and behavioral scientists have been at the forefront of examining the psychological correlates of multiple ‘critical’ behaviors during the COVID-19 crisis, and sought to develop optimally-effective interventions to promote behaviors that yield adaptive outcomes. This symposium brings together a series of studies that showcases behavioral research in the COVID-19 pandemic with the goal of contributing to the evidence base of determinants of these critical behaviors. The first study reports on the development and validation of the vaccination concerns and beliefs in COVID-19 scale (VaCCs) from first principles, and its association with intentions to vaccinate. The second study outlines a survey examining the social cognition and beliefbased correlates of COVID-19 vaccine intentions and vaccine booster intentions in multiple samples. The third study reports on an innovative theory-based intervention using mental imagery to promote engagement in hand hygiene behaviors to mitigate the spread of the virus. The final study investigates the correlates of panic buying and hoarding behavior in advance of lockdown announcements during the pandemic, with implications for future emergency-related behavior. Taken together, the current research summarizes an innovative program of research that contributes to current knowledge on the determinants of critical behaviors in the COVID-19 pandemic and how, potentially, this can inform future research and practice.