Visitors are integral components of zoological parks and their importance has led to a research area devoted to understanding the people-zoo relationship. This paper reviews, and provides a point of entry into, the literature relating to visitor research in zoos. The field emerged relatively recently and is diverse and interdisciplinary (it shares common ground with sociology, education, psychology, zoology, and other academic disciplines). Several areas can be identified in the literature (audience analysis, circulation and orientation, exhibit evaluation, and interactions with animals), and these areas have revealed visitors' demographic and behavioral characteristics, people's behavioral responses to endogenous and exogenous factors, the impact of exhibit design, and visitors' movements around zoos. Limitations of existing work include independence between research areas, lack of international studies, limited generalizability of results, and the minority status of the field. Therefore, suggestions for future work include integrating different research areas, more research from outside Europe and America, and increased interaction within the visitor research community.