This edited volume presents the first results of a long term research project, funded by the Italian Government, which aims at mapping out the fine functional structure of sentences, nominal phrases, and other major phrases making up sentences. Structural representations are seen to arise from the combinations of two kinds syntactic atoms: lexical elements (nouns, verbs, and adjectives) and functional elements (determiners, complementizers and various kinds of inflections), the first expressing the descriptive content, the second providing the functional architecture of syntactic structures. This study focuses on the latter, exploring in particular the functional structure of dps (determiner phrases, noun phrases having a determiner as its head: thus, the old man would be a determiner phrase headed by the, headed in turn by man, as its dependent) and ips(inflection phrases, another syntactic category to describe clauses without complement clauses: e.g. she married him would be an ip without the complementizer since). These papers also examine the functional structure of sentences in both verbal and signed languages, uncovering a rich hierarchy of functional projections hosting different classes a adjectival phrases. one of the major collective research projects that has emerged from contemporary research in generative grammar, this volume is highly rigorous empirically and theoretically and provides linguists with a very important body of analysis that is likely to influence future research.