In Study 1 of this project, we examined the effect of including a proscriptive versus prescriptive injunction with information about UK government COVID-19 behavioral rules and guidance on intentions to comply with government guidelines, and examined perceived legitimacy of advice as a moderator, in a UK university sample. The results of Study 1 showed that a proscriptive injunction elicited lower intentions to comply with UK government COVID-19 guidelines than a prescriptive injunction. The effect of Injunction Type on intentions to comply with UK government COVID-19 guidelines was moderated by perceived legitimacy. When perceived legitimacy was low, the proscriptive injunction elicited lower intentions to comply with UK government COVID-19 guidelines than did the prescriptive injunction. The findings have implications for the design of public health information.