CFAR, the Core Facility for Aged Rodents, has been a major feature of the University of Michigan Claude Pepper Center since its inception in 1989. CFAR will continue to serve the needs of Pepper Center investigators through four Specific Aims. (1) CFAR will provide advice to all OAIC investigators, from student through faculty levels, in the use of rodents for research into the biology of aging and its role in late life disease. (2) CFAR will support specialized colonies of mice particularly well suited for research on the biology of aging and its relationship to late-life disease. These include (a) genetically heterogeneous mice of the UM-HET3 stock; (b) calorically restricted UM-HET3 mice; and (c) mice of the long-lived Snell dwarf (dw/dw) stock, carrying the Pitl dw mutation. Mice from these colonies will be provided to faculty members working on PESC and RCDC research projects, as well as to Geriatrics Center faculty members who wish to conduct pilot studies on mouse aging supported by other sources of NIA funds. (3) CFAR funds will support the development of new animal models for specific purposes. In the first year, these will include a new fourway cross suitable for studies of late-life hearing loss, and a CAG-repeat knock-in mouse to study the timing of age-dependent motor neuron disease. (4) To nurture new rodent-based research initiatives through Core Development Projects. In the first year two such projects will be supported, one to develop instrumentation for assessment of age-dependent changes in balance and vestibular function, and the other to use calorically restricted and dwarf mice to evaluate the role of aging and anti-aging interventions in skin cell proliferation and pro-neoplastic transformation. The CFAR director will also play a role in helping to develop and design RCDC and PESC projects that make use of rodent models.