The main challenge for the transition to the formal economy is finding the right policy mix that corresponds to the diversity of characteristics and drivers of informality. Reliable and relevant statistics are needed to better understand these complex aspects of informality and monitor progress towards formalization. In June 2015, the International Labour Conference adopted the Transition from the Informal to the Formal Economy Recommendation (No. 204), the first international labour standard which focuses on the informal economy in its entirety. That same year, in September, the United Nations adopted the 2030 Agenda for Sustainable Development, which included the transition to formality in the targets for Sustainable Development Goal 8. These two instruments represent major milestones in the global approach to formalization, particularly by providing guidance on the process. The ILO has made the formalization of the informal economy one of its strategic outcomes and supports tripartite constituents in facilitating the transition to the formal economy at the national level. This report forms part of the ILO follow-up plan of action to support the implementation of Recommendation No. 204. It is all the more timely given that the United Nations General Assembly has recently approved the Global Indicator Framework to monitor the Sustainable Development Goals, including a specific global statistical indicator on informal employment (8.3.1). The report provides for the first time a statistical profile of the informal economy at the global level using a common set of operational criteria to measure informal employment and employment in the informal sector for more than 100 countries, including both developed and developing countries. Statistics on informal employment are disaggregated by sex, age, level of education, status in employment and other socio-economic characteristics.