This chapter examines the nature of the research conducted in and on zoos. Much of the research undertaken in zoos is concerned with the behaviour, nutrition, welfare and reproduction of animals. However, work has also been published on the history of zoos, their place in culture, their conservation role, their educational value and the interactions between people and animals in zoos. Historical trends in zoo research are examined along with taxonomic bias in the species studied: most studies involve mammals. Although zoo research is published in a wide range of journals, in recent decades a number of specialist journals have been produced.