Data2X, named for the power women have to multiply progress in their societies, aims to advance gender equality and women’s empowerment through improved data collection and analysis that can provide a solid evidence-base to guide development policy. To provide basic information for a Data2X roadmap, this report maps gender data gaps in developing countries across five domains of women’s empowerment: (1) health, (2) education, (3) economic opportunities, (4) political participation, and (5) human security.