Mandarin, as other classifier languages, usually requires a classifier when numerals, quantifiers, or demonstratives are present, but also allows bare classifier-nouns (CL-N) without any determiners. This paper examines two empirical questions: (i) What is the structure of CL-N that can account for its behavior? 2 Mandarin Bare Classifier-Nouns: Towards a Universal Structure for P HRASES carrying quantity information. This proposal correctly predicts that CL-Ns and Num-CL-Ns have different distributions due to different structures. Supporting data are drawn from CL-Ns in argument and non-argument positions in various constructions to attest the prediction that when the quantity information is needed in the discourse, Num-CL-Ns will be obligatory; in contrast, when the quantity information is not crucial, CL-Ns will be preferred or obligatory.