Discussion during the last twenty-five years has made the relation of Latin to Osco-Umbrian a problem, where none had previously existed. Until about that time, the assumption of a unity later than West Indo-European-Uritalisch or Proto-Italic-from which both Latin and Osco-Umbrian were derived, was universally accepted; it is still the doctrine to be found in the standard handbooks of Indo-European. During the last quarter-century, however, this hypothesis has been repeatedly called in question by Italian and German linguists, and there are now many who regard Latin and Osco-Umbrian as essentially two separate branches of the Indo-European family. Since this problem, so far as I know, has not been the subject of a full-length treatment in any American journal, a review and an evaluation of the recent arguments may be of interest.