This paper investigates the place of Vietnamese in the binary NP/DP typology as formulated by Bošković (2005, 2008, 2009, 2010). Vietnamese patterns with NP languages when it comes to its lack of a genuine definite determiner, the presence of radical pro-drop, and its lack of number morphology, but it patterns with DP languages when it comes to the presence of TP, subject expletives, and subject-object extraction asymmetries. The mixed status of Vietnamese suggests that the difference between article and article-less languages might not be as straightforward or clearcut as Bošković claims. In fact, the way these properties pattern in Vietnamese reveals that there are at least three smaller parameters (nominal, clausal, and quantificational) at stake, not just the presence or absence of DP, and that these three are independently fixed as [-DP], [+TP], and [-movement], respectively. Also important is the fact that Vietnamese is a topic-prominent language.
