This Climate Public Expenditure and Institutional Review (CPEIR) Methodological Guidebook seeks to equip relevant stakeholders (governments, donors, CPEIR practitioners) with information on a step-by-step process, methodologies and tools to conduct a CPEIR. In particular, this Guidebook reviews the processes and methodologies used in the 19 CPEIRs done to date and proposes a common framework for future CPEIRs. As such, this CPEIR Methodological Guidebook provides readers with background on context, purpose, process and tools in implementing a CPEIR together with an overview of the key challenges typically faced during the CPEIR implementation.