What is evaluation? Why is it important in public health? How can evaluation lead to improved health outcomes? Evaluation and evidence-based practice are core to professional practice within the wider public health field. 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. Conducting evaluation can be challenging. Furthermore, the move to evidence-based practice demands that practitioners are able to critically interpret published evaluation findings. "Evaluation" is a readily accessible examination of the key theories and principles underpinning 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, including: identifying indicators of success; developing an evaluation plan; ethical issues; and making the most of findings. This book is the first in a series on current theories and concepts for those working within the wider field of public health.