This paper examines the frequently discussed quantifier dou 'all' in Mandarin Chinese. I argue, following traditional grammarians as well as Lee (1986), that dou 'all' is an adverb of quantification. I show that a floating quantifier analysis of dou 'all' along the lines of Chiu (1990, 1993) falls short of accounting for the dual status of dou, as a quantifier and a binder. As a quantifier, dou quantifies over regular NPs (plural). As a binder, dou provides quantificational force for wh-polarity items, which do not have inherent quantificational force. I argue that the locality restrictions associated with dou varies depending on the element it is associated with. With regular NPs, the locality is reflected by LF adjunction of dou. With wh-polarity items, the locality is restricted by licensing of polarity items as well as its ability as a binder. © 1995 Kluwer Academic Publishers.