China proposed the Belt and Road Initiative in 2013 to improve connectivity and cooperation on a transcontinental scale. This study, by a team of World Bank Group economists led by Michele Ruta, analyzes the economics of the initiative. It assesses the connectivity gaps between economies along the initiative's corridors, examines the costs and economic effects of the infrastructure improvements proposed under the initiative, and identifies complementary policy reforms and institutions that will support welfare maximization and mitigation of risks for participating economies.