In 2019, the Harvard Museum of Comparative Zoology acquired The R. Glenn Northcutt Collection of Comparative Vertebrate Neuroanatomy and Embryology, which comprises an estimated 500,000 histologic sections and whole mounts prepared and mounted on glass slides. Assembled by Professor Northcutt between 1963 and 2014 to reveal the microscopic anatomy of the nervous system and related tissues, the collection additionally includes valuable slide series prepared by other neuroanatomists, including John Black Johnston, Othmar Solnitzky, and David Senn. Most included specimens are serially sectioned whole or partial brains for comparative cytoarchitectonic studies. There also are series of entire heads and hundreds of serially sectioned embryos representing 22 genera for studies of the development of sensory systems and cranial nerves. The collection is scientifically unique in its taxonomic breadth: the more than 240 genera and 270 species included represent all major groups of living vertebrates as well as two key out-groups, acorn worms and cephalochordates. Particular strengths include hagfishes, lampreys, chondrichthyans, basal actinopterygians, basal sarcopterygians (including all genera of lungfishes and the coelacanth, Latimeria), amphibians, and tuatara (Sphenodon), and many families of squamates, turtles, crocodilians, marsupials, and primates. Ongoing curatorial activities are generating digital whole-slide images of most of the collection, which are accessible via the Internet. Here we briefly describe the history of the collection and its scientific importance, methods used to prepare slides, ancillary materials, doctoral and postdoctoral students and visiting scientists who utilized it in their studies, a partial list of publications based on the slides and, finally, a taxonomic inventory of the collection and related information that will facilitate its use in research and education.