BackgroundPreventive behaviors continue to play an important role in reducing the spread of the SARS-CoV-2 virus.PurposeThis study aimed to apply the reasoned action approach (RAA) to predict Covid-19 preventive intentions and behavior and to test whether temporal stability moderates relations between RAA constructs and behavior.MethodsA representative sample of UK adults (N = 603) completed measures of RAA variables (i.e., experiential attitudes, instrumental attitudes, injunctive norms, descriptive norms, capacity, autonomy and intention) in relation to six Covid-19 preventive behaviors (i.e., wearing face coverings, social distancing, hand sanitizing, avoiding the three Cs [closed spaces, crowded places, and close contacts], cleaning surfaces, and coughing/sneezing etiquette) at baseline (December 2020) and after 1 month. Self-reported behavior was assessed at baseline and after 1 and 2 months.ResultsThe RAA was predictive of Covid-19 preventive intentions at time 1 and time 2; instrumental attitudes, descriptive norms, and capability were the strongest predictors at each time point. The RAA also predicted subsequent behavior across time points with intention, descriptive norms, and capability the strongest/most consistent predictors. Temporal stability moderated a number of RAA–behavior relationships including those for intention, descriptive norms, and capability. In each case, the relationships became stronger as temporal stability increased.ConclusionsHealth cognitions as outlined in the RAA provide appropriate targets for interventions to promote Covid-19 preventive intentions and behavior. Moreover, given that continued performance of Covid-19 preventive behaviors is crucial for reducing transmission of the SARS-CoV-2 virus, the results highlight the need for consistent messaging from governments and public health organizations to promote positive intentions and maintain preventive behavior.