Evaluation and evidence-based practice is core to a professional practice. Practitioners in a range of sectors, including the voluntary sector, are increasingly being held to account for the success of projects and programmes of activity. Many practitioners lack confidence in conducting evaluation. Furthermore, the move to evidence-based practice demands that practitioners are able to critically interpret the findings of evaluations. Evaluation is an accessible and understandable examination of the key theories and principles underpinning core approaches to evaluation. It offers a guide to how these principles can be implemented in practice and provides insights into dealing with some of the real-life challenges and complexities of evaluation.