First Published in 1988. Throughout this book 'enquiring teachers' is taken to mean those who are students on courses, successful completion of which depends in part on their undertaking one or more enquiries into their own practice or that of their colleagues. This Introduction presents some definitions and then discusses the implications for teachers who become students on enquiry-based courses, for the schools and colleges in which they teach and for the colleges, polytechnics, universities and teachers' centres which mount and teach the courses.