The purpose of this dissertation is to explain the syntax and morphology associated with mixed categories in which both verbal and nominal projections are apparently headed by a single word. Though the mixed categories seem incompatible with a linguistic generalization about categorial identity between heads and projections (i.e., X-bar theory), I claim that the linguistic generalization is tenable at the level of constituent structure. Rather, following head sharing analysis (Bresnan 1997), I argue that the mixture of verbal and nominal properties arises as a consequence of mapping a constituent structure of a head and that of its sister to the same functional structure, within a framework of Lexical Functional Grammar.

This dissertation focuses on mixed categories in Japanese. In this language, mixed categories involve mixed case marking in which both a nominal case (i.e., genitive) and a verbal case (e.g., nominative or accusative) are assigned to arguments of a single predicate. They are problematic regarding a generalization such that the nominal case is licensed only within a nominal projection, while the verbal case is licensed only within a verbal projection. I argue that the mixed case marking is allowed only in a verbal projection. Assuming a phrase structure rule, which enables a sister of a predicate to bear a nominal case even in a verbal projection, I show that a head sharing analysis fits well with Japanese mixed categories.

This dissertation also discusses morphology in Japanese mixed categories. I carefully examine lexical integrity of head elements in mixed category constructions from both a phonological and morphological viewpoint. The result suggests that the head of Japanese mixed categories is a single verb, which is derived from the concatenation of an argument-taking noun and a verbalizing suffix.

I chiefly deal with Temporal Morpheme Constructions in which a Temporal Morpheme such as tyuu ‘during’ is combined by a preceding argument-taking noun to form a single predicate. I also extend my analysis to other mixed categories such as Purpose Expressions and Nominalized Adjective Constructions, which involve control structures. In addition, I reexamine the so-called post-syntactic compounds, regarding them as a variant of mixed categories.