Systematics underpins all of biology. Cladistics is a method of systematic classification that has become applied to comparative studies in all fields of biology. In cladistics, the genealogies that are reconstructed are based on common ancestry rather than on overall similarity. True phylogenetic relationships are thus revealed. To meet the need for training, the Systematics Association has sponsored a short course on cladistics. The interest sparked by this course was such that the course material has been gathered together in this book, now available in paperback. To introduce the subject, the principle of parsimony and methods for character coding and determining character polarity are first presented. Methods of cladistic tree-building follow, and tree statistics are detailed. Alternatives to parsimony, molecular applications of cladistics, and the relevance of fossils are then discussed. The concluding chapters review two important topics in cladistics: cladistic biogeography and the implementation of cladistics results in systematics. This book provides an up-to-date account of the techniques of modern cladistics, written in a clear, readable style. As such, it should be an invaluable text for all students interest in systematics and comparative studies.