Evaluation matters. In an increasingly complex and challenging environment for international development and partnership, the importance of demonstrating results and learning from the European Commission’s (EC’s) external assistance is critical. Evaluation is a key learning tool for the EC to understand not only what works and what does not, but why and under what circumstances. Evaluations generate knowledge and produce evidence which we use to improve the way we engage with our partners and enhance the impact of our development cooperation. As one of the world’s largest donors, the European Union (EU) is a leading force in demonstrating the value of rigorous evaluation. The EU is committed to embedding an ‘evaluate first’ culture (EC, 2013), premised on using evaluation as an indispensable tool to inform its choices and decisions with the best available evidence and thereby improve its strategies and practices. This handbook is a revision of the Methodology Guidance published in 2006 and reflects the significant progress made in the field of evaluation over the past two decades. The handbook is a living document that will be adapted over time to reflect evolving practice and needs. It will also be made available as a web-based platform.