Financial inclusion, defined as the proportion of individuals and firms that use financial services, has become a subject of considerable interest among policy makers, researchers, and other stakeholders. In recent years, some 50 countries have set formal targets and goals for financial inclusion. If not implemented properly, efforts to promote financial inclusion can lead to defaults and other negative effects. This Global Financial Development Report (GFDR) provides a careful review and synthesis of recent and ongoing research on financial inclusion, identifying which policies work and which do not, as well as areas where more evidence is still needed. Despite the growing interest, the views of policy makers and other financial sector practitioners on the policies that work best are widely split, underscoring the major gaps in knowledge about the effects of key policies on financial inclusion. This GFDR introduces new data and research and draws on available insights and experience to contribute to the policy discussion. The rest of the report consists of three chapters, covering, (1) the importance of financial inclusion, some key facts, and drivers of financial inclusion; (2) financial inclusion for individuals; and (3) financial inclusion among firms. Within these broader topic areas, the report focuses on policy-relevant issues on which new evidence can be provided. A statistical appendix consists of the following three parts: appendix A presents basic country-by-country data on financial system characteristics around the world; appendix B provides additional information on key aspects of financial inclusion around the world; and appendix C contains additional data on Islamic banking and financial inclusion in member countries of the Organization of Islamic Cooperation.