Human beings' responsibility to and for their fellow animals has become an increasingly controversial subject. This book provides an overview of the many different perspectives on the issues of animal rights and animal welfare in an encyclopaedic format. Students, teachers, and interested readers can explore the ideas of well-known philosophers, biologists, psychologists, animal rights activists and historians such as Peter Singer, Tom Regan and over 125 others, all of whom have contributed original entries to create a multi-disciplinary work. Users are able to examine critically the varied angles and arguments and gain a better understanding of the history and development of animal rights and animal protectionist movements around the world.