The experimental use of small New World primates such as the tamarin and marmoset has provided new challenges in nutrition and husbandry for primate colony managers. Because Saguinus oedipus oedipus is an endangered species, successful captive breeding will be vital to continued experimental use of these animals. Unlike rodent populations which can be maintained satisfactorily in more or less routine and easily prepared and maintained animal facilities, the marmoset presents a variety of problems that must be understood and which, in most instances, have not been addressed. Issues pertinent to successful maintenance and production of these species include type of facilities for housing and breeding, nutritional requirements, behavioral patterns, breeder selection and climatic sensitivity and controls. In addition, costs have escalated both in animal purchase price and in maintaining a suitable colony facility. Whereas Old World monkeys have been maintained and bred in captivity for some time, only a few colonies of Callitrichidae exist. Colony personnel have focused on research investigations with little emphasis on husbandry and nutritional needs; these have been often addressed by word of mouth between colony managers and the trial-and-error approach. Consequently, many different approaches in colony management are used with varying degrees of success. The annual informal meeting of marmoset colony managers at the American Association for Laboratory Animal Science meeting has provided a sounding board for problems and concerns; the compilation of information regarding the various colonies and their practices by Morin (personal communication) has served as a clearinghouse of