Linguistic studies of idiomatic expressions (lEs) are cited to show that idioms can be systematized and analyzed at morphosyntactic, semantic, and pragmatic levels; characteristics of Portuguese lEs are described, and it is contended that lEs are metaphoric constructions crystallized by use and cultural tradition. Neglect of IEs in French and Portuguese dictionaries and grammars is criticized, and recommendations are made for the teaching of IEs in foreign-language courses. In the case of the European languages, many IEs have exact target-language equivalents and may be taught from the beginning; imprecise equivalents belong to an intermediate stage and IEs without equivalents, to an advanced stage. Expressive values of IBs are outlined, and controversy over their acquisition is discussed. (Copyright 1996, Sociological Abstracts, Inc., all rights reserved.) (LLBA 1996, vol. 30, n. 4)