Impact evaluation is a methodology designed to determine whether a program or intervention actually caused observed changes in outcomes. It goes beyond measuring “what happened” to answer: Did the intervention make the difference? How? And why?

This brief introduces the core concepts of impact evaluation, including types of evidence, selection bias, randomized controlled trials (RCTs), and theory-based evaluation (TBIE). It features practical examples from the education sector, with tools and strategies for using evidence to make smarter decisions, and design better programs.

Designed for practitioners, policymakers, and researchers, this guide offers a practical and rigorous approach to understanding what works—and why—in education and social development.