The Pandemic Anxiety Inventory (PAI) assesses anxiety symptoms individuals attribute to the presence of a pandemic. We conducted this study of 379 British adults during the COVID-19 pandemic and found that the PAI exhibited excellent reliability and solid criterion validity. Pandemic anxiety was associated with reduced social support, anticipated life changes, financial strain, job loss, economic insecurity, and the hospitalization or death of a close friend or relative. Using correlational and bifactor analyses, we found that the PAI demonstrated solid convergent and discriminant validity. The findings suggest that the PAI can be used in research and clinical practice.