Laws alone are not enough to protect girls from violence. Despite being illegal throughout the world, in many places the use of violence against girls is not only widespread, it's socially acceptable.
Gender power dynamics mean that these social norms are defined by men. That's why more must be done to change how boys and men view themselves.
Here three experts who work with boys and men talk about out how redefining gender norms - particularly male perceptions of masculinity - can reduce violence against girls.
Meet the experts
Gary Barker is international director of Promundo, an NGO that aims to reduce violence against young people in Brazil, Rwanda and the US. He has written about gender and violence in Latin America, sub-Saharan Africa and Asia and has also consulted for the World Bank, UN and World Health Organisation.
Molly Melching is founder and executive director of Tostan, an international NGO headquartered in Senegal whose mission is to bring about sustainable community-led development in African communities. They work in eight countries (and in 22 different languages) to provide non-formal education for both adolescents and adults, including boys and men.
Annabel Erulkar is country director in Ethiopia for the Population Council, which runs Addis Birhan (which means 'New Light' in Amharic). Addis Birhan works with the husbands of child brides to change gender norms.
Why is engaging with boys and men to redefine gender norms so important?
Gary: "Reducing violence requires an understanding of men's experiences of violence in childhood, which are often the root cause of the violence they show against girls and women. We saw from our research that issues affecting women's lives - such as violence - also affect men, albeit in different ways. Yet when we started in 1999, there was little concrete work being done with boys and men. So we began engaging with them in order to transform how they see themselves and to encourage them to believe in gender equality."
Molly: "We made the decision to include boys and men early on because, understandably, when we just began working with girls and women about their rights, the boys and men felt excluded and suspicious. So we stopped talking about girls' rights and women's rights and we started talking about human rights, and specifically discussing the fact that men, women and children all have the same rights and responsibilities."
Annabel: "Early marriage is common in the rural area of Amhara in Ethiopia and we started a safe-spaces programme for married adolescent girls called Meseret Hiwott (Amharic for 'Base of Life'). After a few months the husbands of the girls requested their own group. We saw it as an opportunity to change gender norms in the household, so we started Addis Birhan."
How does your programme get boys and men to change their perceptions of masculinity?
Annabel: "Our curriculum for husbands focuses on helping men form more equitable and supportive relationships with their wives. The curriculum covers issues such as reproductive health, HIV and family planning, support of healthy and happy families, non-violent communication, domestic violence and alcohol and drug abuse."
Molly: "Tostan implements a human rights-based programme that allows for dialogue on gender and equality. Through non-judgmental discussions in the classroom and then in the extended social network, boys and men start changing their attitudes related to their traditional roles and responsibilities."
Gary: "We work at a community level to promote men's involvement in women's lives in positive ways. That means involving them in sexual and reproductive health, women's empowerment and care giving."
How do you recruit boys and men into the programme? Have the communities you work in embraced it or has there been resistance?
Molly: "We learned early on that it's critical to do the programme in as many communities as possible in the same area. If one village alone is changing and they go to the well or weekly market and start talking about new ideas, someone who's never discussed this is going to be shocked. But if there are 40 communities in an area, and you can do the programme in ten, it really makes for a critical mass of people who understand about human rights and want to bring about social change together. We're in about 800 communities right now across eight countries. Sixty people (women, men and adolescents) in each community attend class sessions and they then reach out to at least 60 more in their community to share what they have learned."
Gary: "By partnering with boys and men who already believe in gender equality we're able to engage other men with our community campaigns - such as the Mencare campaign, which encourages men to embrace fatherhood - and group education sessions, which we design with community members."
Annabel: "Male mentors recruit husbands in rural areas of the Amhara region by going door-to-door to explain the project. Participating husbands are then formed into groups that meet in their villages."
Have you seen evidence that engaging with boys and men in this way has changed perceptions of gender roles? And does this reduce violence against girls and women?
Molly: "After implementing a three-year programme in 39 communities in Guinea-Bissau, 157 communities in three different regions decided to abandon female genital cutting and child marriage, and to promote human rights. We've seen communities that we've worked with stage peaceful marches where they say 'we do not accept that this man hit his wife' and they call in journalists to tell them this is not acceptable in their community."
Annabel: "Our research has found that girls who take part in Meseret Hiwott experience improvements in all areas, including family planning use, equitable division of labour in the household and the husbands' accompaniment of his wife to the clinic. When husbands also participated in Addis Birhan, there were further improvements in these outcomes. For example, when both husband and wife participated in the groups, 81 per cent of girls reported that their husbands now help with domestic work. This is compared with 59 per cent when only girls took part and 33 per cent among non-participants."
Gary: "Our work to engage men in care giving has been key in women reporting having more time to invest in their careers and improvements in equitable household decision-making. We've consistently found increased care giving and contraceptive use among the boys and men we work with, as well as changes in attitudes and reductions in violence."