This new study on modality in English represents a departure from more traditional approaches to the subject, where the modal auxiliaries have been the usual focus of attention, by examining in detail the nature of their association with different categories of modal adverb. Modality is notoriously complex but the present work offers an accessible introduction to the topic, a comprehensive account of modal-adverb co-occurrence, and a reappraisal of the English modal system. The descriptive framework draws fresh insights from syntactic, semantic and pragmatic approaches to the study of language and communication, and from recent work in corpus linguistics. The book includes contrastive reference to the expression of modality in Spanish and a discussion of modality in such applied contexts as language teaching. A major feature is its reliance on authentic spoken and written language data. The study is suitable for undergraduate and postgraduate students of linguistics, English language, communications studies and related disciplines.