Ecological diversity, or the variety and abundance of species in different habitats, is one of the central themes of ecology. However, much of the existing literature on this subject is diffuse, often confusing and beset by unnecessarily complicated mathematics. This book aims to provide a succinct and clear summary of the relevant literature and a practical guide to the measurement of diversity. It discusses the methods of describing ecological diversity in conjunction with specific recommendations for the selection and interpretation of diversity measures. In addition the book considers the sampling problems often encountered in ecological censusing. The work concludes with a discussion of the empirical value of diversity measures. A special feature that makes the book particularly accessible to readers without great expertise in mathematics is the inclusion of worked examples of the main diversity measures and models. The book should appeal to students taking advanced courses in ecology and also to professionals working in conversation and related areas of applied ecology.