ABSTRACT In a large class of languages there are sentences in which verbs appear in non-canonical positions. These phenomena have recently been analyzed in terms of verb movement, a process that raises unique empriical and theoretical questions. The movement of heads (such as verbs) displays very special properties which differ from the movement properties of phrasal categories, which have been a major focus of syntactic research from the inception of generative grammar. The movement of verbs is strictly local and displays significant variation from language to language. The central empirical question is whether verb movement processes manifest a single unique grammatical operation across construc- tions and across languages. The central theoretical issue is whether the observed locality and variation can be reduced to the principles governing the behavior of phrasal categories. Three ideas lie at the center of the research. First, there are two types of verb movement processes: one moves the verb to an auxiliary position, the other moves it to a presentential position. Second, these movements leave behind traces which are subject to a head government condition which operates in the phonology and, possibly, to the Binding Conditions in Logical Form. The third idea is that the classical notion of movement should be reinterpreted in terms of relatedness among multiple representations. This involves generalizing the notion of derivation in terms of the concept "delocalized" category. These central ideas can be formally realized in many different ways. The correct formulation will be shaped by the need to parameterize the emerging theory so that it accommodates the observed variations appropriately. The parameterization must be responsive to both synchronic variation among languages and diachronic relationships among stages of a given language. Extensive work on variation among the Romance and Germanic languages and on the history of English and French strongly suggests that differences cluster in identifiable subgroups which reflect a small number of underlying parameters. The project focuses on a related set of central issues in contemporary linguistic theory. The investigators will examine a number of different languages and attempt to develop and refine a theoretical model of grammar which can account for the variations among them in a thorough and parsimonious way. A successful outcome of the project would provide a significant advance in our understanding of the underlying nature of language, and hence of the human mind.