Neoplagiaulacidae is a family of mammal within the extinct order Multituberculata. Fossil remains are known from the Upper Cretaceous through to the latest Eocene/early Oligocene. Representatives have been found in North America, Europe and Asia. They are the last multituberculates known. Neoplagiaulacinae (Ameghino 1890) has been seen as a sub-family within Ptilodontidae (Cope, 1887). More recent thinking has it as a family. Synonyms are Ectypodidae (Sloan & Van Valen 1965) and Ectypodontidae (Sloan & Van Valen 1965). Most fossils are restricted to teeth. The family is part of the suborder of Cimolodonta within the superfamily of Ptilodontoidea.