Mouse models have played, and continue to play, an essential role in type 1 diabetes research. Many of the major advances in our understanding of the immunopathogenesis of type 1 diabetes have resulted from studies performed in appropriate mouse models. Indeed, many of the new concepts for prevention and treatment of type 1 diabetes have been first validated in experimental studies. It is thus essential that investigators interested in type 1 diabetes have access to mouse models of the disease and the opportunity to develop new strains as appropriate. The Immunology Core provides investigators access to these essential resources. The Core consists of two components: i) The Genetics component provides service in the development of mouse strains relevant to the study of type 1 diabetes (transgenic mice and mice with genetic mutations) using recombinant DNA technology. The Genetics component of the Core is part of a Washington University facility used exclusively for immunological studies, ii) The Animal component provides a wide range of diabetes-susceptible inbred strains of mice for immunological analysis. Its purpose is to maintain and make available a wide range of inbred strains of mice. Some of the strains are generated by the Genetics component, but investigators outside our institution may provide others. The usual modus operandi is that the choice of strains to develop is made by the investigators who then finance, through their own independent research support, the creation and maintenance of the mouse strain. Once the desired mouse strain has been produced, the Core provides investigators with access to an experienced mouse geneticist who supervises the breeding programs, the maintenance of the lines and carries out, if needed, the embryo freezing. Thus, the Core serves as a central cataloguing and depository of a wide range of important strains. The DRTC contributes to the finances of the facility together with the Departments of Pathology and Immunology and the Department of Medicine. As explained in the Budget section, the DRTC contributes about 20% of the costs of this Core. This arrangement enables any funded DRTC investigator doing immunological studies on autoimmune diabetes immediate access to the substantial resources and expertise of the Core.