Measurement and evaluation is core to good impact practice. It helps us understand what works, how it works and how we can achieve more. The authors of the study researched the latest changes in theory and practice based on both new and older, renascent ideas. They spoke to leading evaluation experts from around the world, to ask what’s exciting them, what people are talking about and what is most likely to make a long lasting contribution to evaluation. The result is new thinking, techniques, and technology are influencing and improving practice.