The holotype of Microvenator celer Ostrom, 1970 (AMNH 3041) is a partial skeleton of a small maniraptoran theropod from the Lower Cretaceous Cloverly Formation of Montana. We present a detailed redescription of this specimen, em-phasizing those features that are of interest for discovering the phylogenetic relationships of Microvenator. Based on several postcranial features, especially the lack of fusion of the neurocentral sutures, we consider AMNH 3041 a juvenile individual. Reexamination of the holotype revealed the presence of several autapomorphies that provide the basis for a revised diagnosis of Microvenator celer. Diagnostic characters include posterior dorsal and caudal vertebrae'that are wider than high, the presence of a deep depression on the proximomedial part of the pubis, and an accessory trochanteric ridge below the lesser fem-oral trochanter. Phylogenetic analysis places Microvenator either among Oviraptorosauria, or as the sister group to the Oviraptorosauria. Among the characters diagnostic for the Oviraptorosauria, anteriorly concave pubes, a proximodorsal tuber-cle on the manual unguals, and possibly an edentulous dentary with a pronounced symphysis are present in Microvenator. M. celer is the earliest known oviraptorosaurian or oviraptorosaur-like theropod represented by diagnostic skeletalremains.