This chapter examines the contributions that research in zoos has made to zoology. Much of the research conducted in zoos is concerned with the biology of captive animals. However, zoos can also be used to study the basic biology of little-known species and those that are difficult to study in the wild because they are very rare, difficult to find or for some other reason. Many of the early anatomical studies were performed on animals that died in zoos. In addition, zoo studies have included work on animal physiology, genetics, ecology, evolution, behaviour, animal personality and cognition. Some zoos have built specialist research facilities that allow carefully designed experiments to be conducted in controlled conditions in facilities integrated into exhibit designs.