Since their discovery by Western explorers traveling to Madagascar in the 17th century, the ruffed lemurs have undergone numerous taxonomic revisions. During the 19th and 20th centuries, it was intermittently suggested that black-and-white and red ruffed lemurs hybridize in nature. Despite the fact that a natural hybrid zone has never been documented, this suggestion has played a large role in designating the two forms as subspecies of the single species Varecia variegata. Through a review and synthesis of historical documents, taxonomic literature, museum collections, menagerie and zoo records, recent survey work, genetic data, and vocalization data, we examine the evidence for a natural hybrid zone and suggest taxonomic revisions. Our work indicates a more extensive hybrid zone than previously suggested—but one in which hybridization is the exception rather than the rule. Furthermore, our findings warrant upgrading the black-and-white ruffed lemur and the red ruffed lemur from subspecies to full species, Varecia variegata (Kerr, 1792) and Varecia rubra (E. Geoffroy, 1812). Our results support the current captive breeding practices of U.S. and European zoos participating in the ruffed lemur “Species Survival Plan” and the “European Endangered Species Programme”. Lastly, and possibly most importantly, we can now set specific geographic priorities for conserving the habitat of these highly endangered lemurs in northern Madagascar.