This volume is a collection of papers concerning the biology of large branchiopod crustaceans: Anostraca, Conchostraca, and Notostraca. Many of the individual papers were first presented at the Third International Large Branchiopod Symposium (ILBS-3) held at the University of San Diego, CA, USA, July 15-18, 1996. Contributions on additional topics from participants at the symposium, and from colleagues not able to join us in San Diego, are also included. In addition, there is a supplement to the 1995 ‘Checklist of the Anostraca'. The theme of the ILBS-3 was ‘understanding and conserving large branchiopod diversity'. Researchers from around the world presented papers on a variety of topics related to conservation of large branchiopods, with contributions ranging from alpha-taxonomy and zoogeography to community structure and studies of ecology and evolution. One important issue developed in many of the papers in this volume is the need to advance our understanding of basic aspects of branchiopod biology throughout the world in order to enhance our efforts to conserve them. Although we have made important strides in understanding the biology of large branchiopods, we have, with few notable exceptions, made little progress in assuring the conservation of their diversity. We hope this volume will supply the reader with new ideas, and generate enthusiasm for research and public education efforts on behalf of branchiopod conservation.