This book explores a major issue for library and information service managers of all kinds – evaluating the impact of services. When we introduced the first edition of this book we noted that all types of libraries and information services traditionally collect a range of performance information that can tell you as managers something about the efficiency of your services but that a sustained focus on impact was rare, despite the fact that impact evaluation (or as it is sometimes called, outcomes-based evaluation) had recently taken on new importance. What is interesting now is how many library managers are ready to move on to focus on effectiveness of services, or the impact of services on users, including remote users.

Why do we need a second edition of the book? The world of library impact evaluation has changed substantially in the past six years. There are more international and national efforts to engage with the impact of library services on users and, as a result, we now know more about the areas in which libraries of all kinds can make a difference to the lives of their users, as we show in a fully revised and updated Chapter 3.

One thing that hasn't changed much is that library and information service managers still find it hard to get a grip on the slippery concept of service impact and many still struggle when trying to address impact questions in their planning. We are continuing to help here and are increasingly getting involved with evaluation efforts in a variety of countries, with active support from professional bodies in the field. This work has given us the chance to develop, further test and refine our approach to evaluating impact as presented in the first edition of this book. Our analysis of the issues and our approach to evaluating service impact that has helped managers in public, education, health and ‘special’ libraries and information services are still at the core of this book. The approach is designed to help you to understand, construct and deploy impact indicators that relate closely to what you are trying to achieve. The core chapters take you through our rigorously tested process model for impact evaluation, with tools and examples to equip you with all that you need in order to address your own service impact questions.