Not all harmful practices are social norms or gender norms, and norm change is not always necessary to change harmful behaviours and practices. Increased access to opportunities, services and infrastructure, and legislative and policy reforms can also help shift harmful behaviours. Even where a harmful practice is not itself a norm, powerful indirect social and gender norms may influence the practice. Norm diagnosis1 can help to determine whether a harmful practice is a social or gender norm, or if other indirect norms are an important influence maintaining the practice, in the specific setting where the behaviour takes place. Norm change interventions to address child marriage and early union should be included as part of a comprehensive, multisectoral approach to address harmful practices across the socioecological model.