This second edition of the foundational textbook An Introduction to Applied Linguistics provides a state-of-the-art account of contemporary applied linguistics. The kinds of language problems of interest to applied linguists are discussed and a distinction drawn between the different research approach taken by theoretical linguists and by applied linguists to what seem to be the same problems. Professor Davies describes a variety of projects which illustrate the interests of the field and highlight the marriage it offers between practical experience and theoretical understanding. The increasing emphasis of applied linguistics on ethicality is linked to the growth of professionalism and to the concern for accountability, manifested in the widening emphasis on critical stances. This, Davies argues, is at its most acute in the tension between giving advice as the outcome of research and taking political action in order to change a situation which, it is claimed, needs ameliorisation. This dilemma is not confined to applied linguistics and may now be endemic in the applied disciplines.