This 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 both an accessible introduction to the topic as well as a comprehensive account of modal-adverb co-occurrence and a reassessment of how the expression of modality can be accounted for. 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.