The main topic of this paper is the analysis of new needs for information about customers in the context of international marketing in the 1980's and, especially, in the 1990's. Bernard Cathelat, initiator of life style studies since 1970 and his co-author outline here the principal characteristics of an original method of market segmentation : the Socio-Styles-System. As an operational example of its application, he presents the "Euro- socio-styles" survey including all chapters of life, carried out in 1988 and 1989 in 15 European countries divided into 58 regions. Roger Wyss, the international coordinator of the Europanel network, will bear witness to the interest of market panel surveys in this new type of segmentation and describe the opportunity for a new standard European classification of consumer behaviour. The lecture is illustrated with examples drawn from 18 years of experience with this method and from its first, very recent pan-European application.