Examining the forms of social and moral reasoning adolescents use is important for understanding youth engagement with public health guidelines. The present work examined adolescents' perceptions of social norms and associated reasoning in the COVID-19 context. Participants ( n = 127, M age = 17.00, SD = 0.71) negatively evaluated other teenagers who broke COVID-19 guidelines and reasoned about harm reduction to justify breaking these rules, but also recognised the importance of protecting mental health as one reason to spend time with friends counter to these rules. Further, adolescents reported that they were more likely to engage in public health behaviors compared to their peers or the average teenager, suggesting a social norm of lower engagement with these guidelines. Together, this evidence documents the importance of considering social norms and moral reasoning in framing communication efforts that target adolescents' adherence to public health guidelines.