Reforms in budget formulation that transition to programme-based budgeting can be beneficial to health spending. Such reforms can support better alignment with health sector priorities, provide greater flexibility in the use of funds, and improve transparency and accountability towards outputs. These changes can, in turn, support progress towards universal health coverage by using general budget revenues flexibly to purchase health services. However, evidence from country implementation shows that this transformation does not take place automatically. The primary purpose of this guidance book is to provide key health stakeholders with a better understanding of the design, implementation and monitoring of programme-based budgets in the health sector in low- and middle-income countries (LMICs). The work emerged from a rewarding collaboration between the WHO Department of Health Systems Governance and Financing and regional and country colleagues, independent experts, and the OECD, the World Bank Group and the International Budget Partnership, all of whom contributed extensively to the book’s development.