An application of Pikean tagmemic theory to the problem of theme in English expository discourse. Next to a general introduction to the concept of theme, the book describes an experiment on theme-identification in expository texts, it contains a discussion of some European approaches to theme, and the main part is concerned with the development of J.'s theory of theme: narrative contributions to such a theory (with a discussion of the notion of a 'script'), a hierarchical model of theme according to Pike and Pike (1977: 'Grammatical analysis'), grammatical devices for highlighting theme, and discovering and displaying themes in texts.