The COVID-19 pandemic has provided the opportunity to investigate factors associated to compliance with public health measures. We analysed cross-country data (k = 121, N = 15,740) collected one year into the COVID-19 pandemic to investigate factors related to compliance with COVID-19 guidelines, including social norms, trust, stress, demographic factors, and moral values. We also explored cross-country differences in individuals’ stress, trust in government and science, compliance behaviours, social norms, and vaccine hesitancy. We found that social norms to follow preventive measures were positively correlated with compliance. Compliance was also predicted by trust in government and science, stress, demographic factors, and concern about the moral value of harm and care. Finally, we discuss country-level differences in the associations between predictors and compliance. Overall, results indicate that trust and social norms are critical to the development of programs and policies aimed at increasing compliance with public health measures.