Dou has been seen as a typical example of universal quantification and the point of departure in the formal study of quantification in Chinese. The constraints on dou’s quantificational structure, dou’s diverse uses, and the compatibility between dou and other quantificational expressions have further promoted the refinement of the theory of quantification and sparked debate over the semantic nature of dou. The universal quantificational approach holds that dou is a universal quantifier and explains its diverse uses as the effects produced by quantification on different sorts of entities and different ways of quantificational mapping. However, non-quantificational approaches, integrating the insights of degree semantics and focus semantics, take the scalar use as dou’s core semantics. The quantificational approach to dou can account for its meaning of exclusiveness and the interpretational differences engendered by dou when it associates with a wh-indeterminate to its left or to its right, whereas non-quantificational approaches cannot determine the interpretational differences caused by rightward and leftward association and cannot explain the exclusive use of dou. Despite the differences, the various approaches to dou, quantificational or non-quantificational, have far-reaching theoretical significance for understanding the mechanism of quantification in natural language.