Lexical ambiguity is one of the most intractable problems facing language processing studies and, not surprisingly, it is at the core of research in lexical semantics. The papers in this collection constitute not just a set of diverse yet related articles in this core area of research, butrather make up a unique collection of work on the relationship between logical polysemy, sense extension, and discourse structure. Each paper addresses the following questions: what is the representation of a lexical item such that it may assume different senses? What is it about the representationof a lexical item that gives rise to sense extensions and to the phenomenon of logical polysemy? Three major subthemes run through the papers: the role of pragmatics and discourse in lexical disambiguation; the analysis of logical polysemy as a compositional process; and the treament of senseextension and referential transfer phenomena.