One fruitful line of research has been to explore the local linguistic as well as global rhetorical patterns of particular genres in order to identify their recognizable structural identity, or what Bhatia (1999: 22) calls "generic integrity". In terms of methodology, to date most genre-based studies have employed one or the other of Swales' (1981/1990) move-analytic models of text analysis to investigate whether or not the generic prototypical patterns that he has introduced exist universally. This paper, however, considers the application of the Systemic Functional (SF) theory of language to genre analysis. The paper looks, in particular, at distinctive rhetorical features of English newspaper editorials as an important public "Cinderella" genre and proposes a generic prototypical pattern of text development for editorials or what Halliday and Hasan (1989) refer to as the "Generic Structure Potential" (GSP) of a genre. The results of this study should benefit both genre theory and Systemic Functional Linguistics (SFL) and will be, it seems, of interest not only to applied linguists, but to those involved in education, journalism, and the media.