Since its initiation some twenty years ago Longman Linguistics Library has established itself as a series aimed primarily at an undergraduate and postgraduate student readership. Some of its books serve as introductions to key aspects of the subject, others are more specialised: generally they assume a first year's knowledge of linguistics and lead the reader on from there. In all cases the books are self-contained; they are intended to treat important areas in general linguistics and to be of value for a number of years