Nominal anaphora in Spanish and English

The goal of this dissertation is to argue that three constructions that have traditionally been considered as different (NP-ellipsis in English, NP-ellipsis in Spanish and anaphoric one in English) actually correspond to the same underlying construction.; The grounds to this proposal are the observation that the three structures display the same syntactic and semantic properties and the fact that the two English constructions are in complementary distribution.; I argue that so-called anaphoric one involves NP-ellipsis and propose that one, rather than being an anaphoric element, is inserted in the Number Head in order to give phonological support to the number affix, in a process that I call one-support.; I also propose reconsidering some aspects of current assumptions on NP-ellipsis and propose that only functional heads are subject to syntactic constraints in cases of ellipsis: the elision of the lexical content of the phrase is only subject to identification conditions.; I also propose that indefinite a, numeral one and anaphoric one are one unique element, whose differences can be derived by inserting them in different functional heads.; I extend this analysis to Spanish nominal ellipsis and propose that the differences between English and Spanish constructions are due to the interaction of these factors: morphological properties of functional elements in the DP and the position of adjectives.