This book presents a large-scale corpus-driven study of progressives in 'real' English and 'school' English, combining an analysis of general linguistic interest with a pedagogically motivated one. A systematic comparative analysis of more than 10,000 progressive forms taken from the largest existing corpora of spoken British English and from a small corpus of EFL textbook texts highlights numerous differences between actual language use and textbook language concerning the distribution of progressives, their preferred contexts, favoured functions, and typical lexical-grammatical patterns. On the basis of these differences, a number of pedagogical implications are derived, the integration of which then leads to a first draft of an innovative concept of teaching progressives - a concept which responds to three key criteria in pedagogical description: typicality, authenticity, and communicative utility. The analysis also demonstrates that many existing accounts of the progressive are inappropriate in several respects and that not enough attention is being paid to lexical-grammatical relations.