There is literature dealing with the welfare of animals in general, as well as literature dealing with the maintenance and use of laboratory animals. This book brings together these two topics, focusing to the general and species-specific needs of laboratory animals in the light of their welfare. The book provides material for researchers, lecturers, students and technical staff working with laboratory animals. The authors of this book are leading European scientists in laboratory animal science. The book has two main parts: part one focuses on the general principles of laboratory animal maintenance and experimental use, as well as factors which have to be taken into account when good research is done with animals. The second part is species specific, concentrating on the species most used as laboratory animals. This part gives a comprehensive description of the welfare questions considered to be important for each species under laboratory conditions.