The author's aim in this book has been to enquire into the theory underlying the concept of English for Specific Purposes and, by implication, of any language taught where there is a specification of purpose. - Each of the three main chapters (Learning Purpose, Language Use, and course Design of Methodology) consist of two parts. The first part presents the main argument, while the second takes up issues arising from the argument. The book ends with a fourth chapter which recapitulates and concludes the argument of the preceding chapters.