Social norms are informal rules and shared social expectations that shape individual attitudes and behaviour (Arias, 2015; Marcus and Harper, 2015). Gender norms are social norms that relate specifically to gender differences. A common gender norm, for example, is that women and girls will and should do the majority of domestic work (Marcus and Harper, 2015). This helpdesk report presents studies of programmes that aim to bring about changes in gender and social norms; and changes in wider attitudinal and behaviour. Much of the literature and some programme designs recognise the need to change social norms in order to change behaviours, such as HIV/AIDs prevention and better sanitation and hygiene. The report looks at interventions targeting individual and inter-relational levels (e.g. workshops); community levels (e.g. community dialogue, community mobilisation and youth initiatives); and wider societal levels (mass media and edutainment). It highlights the effects of such interventions, focusing on rigorous evaluations.