The Center for Comparative Medicine can trace its origins to the early 1980s when AIDS was first observed in humans and a similar disease was discovered at UCD in captive macaques and domestic cats. Because related retroviruses were found to cause human AIDS and the animal diseases, investigators at UCD had the unique opportunity to study these animals as surrogates for the human disease. A multidisciplinary team of basic and clinical scientists (about 24 in number) in the Veterinary and Medical Schools joined forces to do collaborative research on human, macaque and feline AIDS. This productive interaction led to UCD being designated as one of the first NIH-funded Center for AIDS Research. This remarkable degree of scientific teamwork prompted UCD administration to plan for a Center for Comparative Medicine, which would become a stand-alone building next to the California National Primate Research Center to house investigators in the Medical and Veterinary Schools who would study AIDS and other chronic infectious diseases. This mission was subsequently expanded to cancer and mouse biology, with the overarching theme of animal modeling of human diseases. Planning for the building began in 1988 and was completed in 1992. Funding for construction of the $16 million CCM was provided by a California bond initiative as part of the Garamendi Act with additional funding from private grants and UCD funds for faculty recruitment and instrumentation. Construction of the 16000 sq ft facility began in 1996 and was completed in 1998. The first Director of the CCM, Stephen W. Barthold, DVM, PhD was recruited from Yale University in 1997 and research activities in the CCM started in 1998. The CCM is a shared facility between Veterinary and Medical Schools accommodating ten core faculty members and their labs.