The thesis of this book is that library measurement needs to move on and away from the idea that it is a process of counting and comparing the resources deployed by our libraries. The current emphasis on output measurement is an improvement but not the answer, refreshing as it is to judge a library by the quantity of what comes out instead of by the quantity of what is put in. The author believes that the nature of the library service is that of a “broad aim” social programme, best judged (evaluated) by gathering “politically significant information on the consequences of political acts”. “Political” here implies that the aims and intentions of those funding, organising and using libraries arise from more than one set of social values and from more than one definition of what the library is, and that they differ in priorities even when they do not directly conflict. Information about the library service will be in the form of a spectrum of measures reflecting the inputs, the processes, the outputs and the impact of the library, relating the various values in various ways. The difficulty in measuring library services, it is argued here, arises from the conflicts and lack of clarity about the aims of the service, and from uncertainty about how the process affects the outcomes. The technical problems of measurement are secondary. Chapter One aims to survey the range of measures available, whilst the rest of the book discusses how they might be used.