In the history of English at least five verbs have been found to mean ‘need’: þurfan, beþurfan, need, behove and mister. By adopting a corpus-based approach, this book studies all of them diachronically, from the origins of the language (c.750) to the end of the early Modern English period (1710). Offers a detailed analysis of the meaning of these five verbs which have been found to mean ‘need’, filling a gap in the literature on modality and shedding new light on grammaticalization theory Spans the period c.750 to 1710, adopting a corpus-based approach to study the verbs diachronically Explores the evolution of necessity meanings in English, identifying regular semantic changes and challenging some well-established statements Provides a detailed grammaticalization analysis, paying attention to the different Present-Day-English modal classes, including marginal and emerging modals