This guide is the 2026 update to the Magenta Book, the United Kingdom Government’s central guidance on evaluation. It provides guidance on scoping, design, conduct, use and dissemination as well as the capabilities required of government evaluators. The revised guide introduces several new and significantly expanded areas of focus to support high-quality evaluation across government.

This global review calls for changes in how we think, act and measure economic success to protect and enhance our prosperity and the natural world and provides a new framework to account for nature in economics and decision-making.

The Magenta Book guides government professionals in designing, managing, and using evaluation to inform policy. It highlights evolving methods, the importance of embedding evaluation early, and its role in improving interventions. High-quality evidence supports better decisions, reduces risk, and fosters a culture of continuous improvement across departments.

This strategy provides an approach to greening financial systems, mobilising finance for clean and resilient growth, and capturing the resulting opportunities for UK firms.

Quality in policy impact evaluation (QPIE) is a supplement to the Magenta Book and provides a guide to the quality of impact evaluation designs. It has been developed to aid policy makers and analysts understand and make choices about the main impact evaluation designs by understanding their pros and cons and how well each design...