This dissertation investigates the structure and interpretation of noun phrases in Thai and other classifier languages, focusing particular attention on whether Thai contains the same articulated functional architecture as languages with articles. I argue that while bare nouns in Thai do not project DP, noun phrases which include classifiers do, and that this DP functions as a phase for cyclic spell-out. It is argued that Thai DPs involve the obligatory movement of the NP, accounting for their noun-initial word order.

A uniform analysis of clausal modification within the noun phrase is provided, driven by an analysis of the particle thîi as a complementizer that derives properties from clauses, with the use of thîi in relative clauses being one instance of this use. The analysis of Thai bare nouns as NPs and thîi as a relative complementizer are reconciled with a head-movement analysis of Thai relative clauses, motivated by empirical considerations. Under this analysis, noun-complement clauses are analyzed as modifiers, on par with relative clauses. The property-operator analysis of thîi is suggested to extend to its occurrence in clefts and infinitival clauses as well.

A further construction is investigated in which modifiers do not combine directly with nouns, but instead follow classifiers, resulting in a definite interpretation. This construction provides evidence for a null determiner in Thai, which is argued to take modifiers as complements, either as CPs or as small clauses. The general prohibition against bare classifiers in Thai, alleviated by the presence of modifiers following classifiers, is argued to follow from a structural economy constraint which prefers definite bare nouns to definite bare classifiers. It is argued that this constraint can also provide a principled account for which classifier languages do and do not allow bare classifiers to occur with nouns.

The ability of quantifiers and their accompanying classifiers to appear discontinuously from their associated noun, or quantifier float, is the final major topic of this dissertation. Scope facts lend themselves to an analysis of quantifier float as a byproduct of Quantifier Raising, the normal movement of quantificational noun phrases to their scope position. Thus, quantifier float is analyzed as movement of the entire DP, with the quantifier and noun occurring in different positions due to the conflicting semantic transparency requirements. A generalization about the availability of quantifier float in classifier languages is presented: only languages in which quantifiers follow nouns allow rightward quantifier float. In light of the proposed analysis, this generalization provides evidence that DP is a phase even in languages that lack articles.