OBJECTIVES: We assess different approaches to seeking consent in research in secondary schools. DESIGN: We review evidence on seeking active versus passive parent/carer consent on participant response rates and profiles. We explore the legal and regulatory requirements governing student and parent/carer consent in the UK. RESULTS: Evidence demonstrates that requiring parent/carer active consent reduces response rates and introduces selection biases, which impact the rigour of research and hence its usefulness for assessing young people's needs. There is no evidence on the impacts of seeking active versus passive student consent but this is likely to be marginal when researchers are directly in communication with students in schools. There is no legal requirement to seek active parent/carer consent for children's involvement in research on non-medicinal intervention or observational studies. Such research is instead covered by common law, which indicates that it is acceptable to seek students' own active consent when they are judged competent. General data protection regulation legislation does not change this. It is generally accepted that most secondary school students age 11+ are competent to provide their own consent for interventions though this should be assessed individually. CONCLUSION: Allowing parent/carer opt-out rights recognises their autonomy while giving primacy to student autonomy. In the case of intervention research, most interventions are delivered at the level of the school so consent can only practically be sought from head teachers. Where interventions are individually targeted, seeking student active consent for these should be considered where feasible.