Agriculture can be an important engine of growth and poverty reduction. But the sector is underperforming in many countries in part because women, who are often a crucial resource in agriculture and the rural economy, face constraints that reduce their productivity. In this paper we document the gender gap in access to and ownership of most inputs, asset and services important for agricultural activities. We focus in particular on education, land, livestock, financial services, modern inputs, information and extension and labour. Across assets and inputs women are disadvantaged. The gap in education has narrowed over the last decades but substantial gaps remain in sub-Saharan Africa and South Asia. For land, the key farm household asset, there are significant gender differences in access to land across regions. Moreover female-headed households also typically operate smaller land holdings than male-headed households, across regions. There are also significant and systematic gender differences with regard to livestock, financial services, modern inputs, information and extension and labour. Gender differences in assets are generally interlinked, for example when female farmers have lower levels of technology this is due to their having less access to land, less access to labour and less access to extension services, not their sex. This also helps explain why women farmers do not necessarily benefit from access to extension services, as some studies have found. The implication of this is that selective interventions are unlikely to be effective.