The modal auxiliaries in English have changed their syntactic and morphological character substantially in the course of their development from Old English to Modern English. The English modals, which had all the formal properties of full verbs in the Old and Middle English periods, have lost these properties and now constitute a special subclass of verbs called ‘auxiliary verbs’. Generative grammarians regard this change as the result of the ‘reanalysis’ of modal as auxiliaries which took place in the Early Modern English period. Several generative grammatical approaches have been proposed to account for this reanalysis of the English modals. In this paper we will review three of these proposals which seem to have particularly important theoretical implications for the study of the reanalysis in question, and point out that they all have some theoretical defect. We will then propose a new analysis of this problem in which it is assumed that the reanalysis of modals into auxiliaries was caused by structural as well as semantic factors. Our analysis lays particular stress on the theoretical importance of the change of the VP structure in English effected by the loss of verbal inflections and claims that this change is a crucial factor in the reanalysis of the English modals.