The Animal Welfare Act of 1985 requires the federal government to establish housing standards to promote the psychological well- being of laboratory primates. Little scientific information exists to guide regulators in the development of such standards. Lack of such information can result in arbitrary, subjective standards that are expensive to implement and yet have no significant impact on the welfare of the animals. This project will determine the effects on psychological well-being of three basic features of housing for laboratory primates that must, for research reasons, be housed in single cages most of the time. The effects of cage size, social contact and exercise will be studied. In addition, the effects of tethering and radiotelemetry, two alternatives to chronic restraint of laboratory primates, will be evaluated. Psychological well-being will be assessed under a number of conditions using recognized hormonal, cardiovascular, immunological and behavioral measures. Individual preferences will be assessed by established behavioral methods. The needs and preferences of wild-reared monkeys of a commonly used laboratory species (Macaca fascicularis) will be compared with those of captive-reared animals of the same species and with wild-reared animals of a different but related species from the same part of the world (Macaca nemestrina). The results will enable primate colony managers and regulatory personnel scientifically to develop caging systems and housing policies that maximize the psychological well-being of the most commonly used laboratory primates.