The way a cat is housed will have a significant impact on its welfare. The range of housing conditions in which cats may be kept include boarding, breeding and quarantine catteries, shelters, research facilities, veterinary practices and the home. Drawing on ethological principles, the evolutionary history of the cat and studies of cats kept in different conditions, the housing requirements of cats are described with regard to the quantity and quality of space, contact with conspecifics and with humans, and the sensory, occupational and nutritional environments. Features specific to research facilities, shelters and the home are considered, as are the advantages and disadvantages of confining pet cats indoors or allowing them outdoor access.