This collaborative project integrates and makes more accessible for research two major collections of comparative vertebrate brain material. These collections, at the University of Wisconsin and at Michigan State University, contain over 275 sectioned and stained brains representing more than 150 species, from 50 taxonomic families from 17 different orders of mammals, selected for their research and evolutionary significance. These brain libraries, containing more than half a million sections mounted on microscope slides, are unique and priceless, involving a preparation investment of millions of dollars over decades. They are the largest collection of their kind in the world prepared by standardized techniques, and contain samples from many rare and now endangered species that could never be duplicated. This project will enhance the accessibility of these samples for neuroscience research and education. New optical and electronic techniques are used to produce a catalog of the collections to publicize and promote the availability of this material for study. Production of this catalog, and subsequent transfer of the two collections together to the Washington DC area to join other major collections of human brain specimens, will be first steps toward integrating a major neuroscience resource in a single site, with adequate research facilities. Further plans include electronic dissemination of the catalog internationally, to allow some study of the general appearance and overall organization of a variety of brains, and decisions about whether to visit the collections themselves for more detailed direct study. The preservation, stabilization and centralization of these valuable specimen will have a major long-term impact beyond simply comparative neuroscience, and will provide a unique contribution by NSF to the Decade of the Brain.