Numeral Classifier Systems considers the functional significance of the Japanese numeral system, its conclusions based on a corpus of 500 uses of classifier constructions drawn from oral and written Japanese texts. Interestingly, although the Japanese system appears to conform at least superficially to universalistic predictions about its semantic structure, this study reports that in actual usage, the semantic role of classifiers is slight — only very rarely do they carry any lexical information unavailable from the context or the noun with which the classifier occurs. It does appear, however, that the system has an important role to play in providing pronoun-like anaphoric elements and in marking pragmatic distinctions such as the individuatedness of referents and the newness of numerical information. For these reasons, the classifier system is deeply involved in a number of subsystems of Japanese grammar, and the demise of the system (sometimes rumored to be impending) would have substantial implications for the structure of the language as a whole.