The absence of adequate gender-disaggregated data and statistics on the incidence of violence makes the elaboration of programmes and monitoring of changes difficult. Lack of or inadequate documentation and research on domestic violence, sexual harassment and violence against women and girls in private and in public, including the workplace, impede efforts to design specific intervention strategies. Experience in a number of countries shows that women and men can be mobilized to overcome violence in all its forms and that effective public measures can be taken to address both the causes and the consequences of violence. Men's groups mobilizing against gender violence are necessary allies for change.