This book investigates nominal arguments in classifier languages. A long-held claim is that classifier languages do not have overt article determiners (D). This book, however, brings to the forefront the theoretical investigation on the typologically unique Nuosu Yi, a classifier language that will be shown to have an overt article determiner. By comparing nominal arguments in Nuosu Yi to those in Mandarin, the book provides a parametric account of variation among classifier languages and extends the account to argument formation in general. This book begins with a detailed examination of bare numeral classifier phrases in Mandarin by comparing them with bare numeral noun phrases in number marking languages, such as English, French, and Russian. The book argues for a unified structure of bare numeral containing phrases with no reference to D across languages as well as for a D-less structure for various types of nominal arguments in Mandarin. It further studies nominal argument formation in Nuosu Yi. The facts from Nuosu Yi essentially alter the landscape of empirical data and constitute an immediate (prima facie) challenge to the proposed analysis of nominal arguments based on the Mandarin data. This book argues that despite the fact that Nuosu Yi has an overt article determiner, this should not force us to change anything about the proposed analysis of nominal arguments. Lastly, the book puts the analysis of Mandarin and Nuosu Yi nominal arguments in a broader, cross-linguistic perspective and develops a parametric account of variation in nominal argument formation in general.