This World Bank Group book is an overview of how 24 developing countries have embarked on the long journey to Universal Health Coverage (UHC). This Universal Health Coverage Study Series (UNICO) offers knowledge and operational tools to help countries tackle UHC in ways that are fiscally sustainable and that enhance equity and efficiency, by providing examples and lessons learnt from the UNICO countries (individual case studies may be accessed at http://www.worldbank.org/en/topic/health/publication/universal-health-coverage-study-series). In these countries, which together represent one third of the world’s population, efforts to achieve UHC have mainly focused on fiscal expansion, accountability, and community health workers. The study finds that most of these countries, except for success stories such as Costa Rica and Thailand, are still struggling with establishing functional integrated care networks. However, the report recommends that developing countries should continue to empower their primary sector as gatekeepers to a well coordinated health system.