This publication presents an analysis of women's role in the sustainable use, development and conservation of animal genetic resources. The importance of small-scale famers and pastoralists as custodians of these resources is well recognized, but has never previously been disaggregated by gender. The differential roles of men and women have largely been neglected in studies of animal genetic resources management, but by piecing together several strands of argument and indirect evidence it can be concluded that women are the main guardians of livestock diversity. Global trends in the livestock sector – particularly the shift from subsistence-oriented to market-oriented production, the sedentarization and disintegration of pastoralism, and the emergence of demand for niche market products – are analysed from the perspective of their influence on gender roles in livestock keeping and animal genetic resources management. Likewise, women's role in the reproductive economy is analysed from the perspective of how this influences the type of livestock they keep. Case studies from many regions of the world illustrate that while to a degree women acquire their role as guardians of diversity by default because of global trends, many also make an active and conscious contribution to the management of animal genetic resources.