Sociology's contribution to our understanding of the Latin American development process has been closely linked to studies on the social structure and stratification of the region and to analyses and interpretations of the various social groups' characters and behaviour. This investigative effort has been directed towards ascertaining the specific forms taken by the structure of social groups and classes in the regi n, since it had been postulated that these traits -which are an inherent part of Latin America- were determinants of the patterns which the development process would follow. The present article reviews the main interpretive approaches which have been or are still being used today by Latin American sociologists for the study of the main social groups' and classes' attitudes and forms of behaviour. The profound nature of the changes now taking place provides grounds for a reconsideration of the hypotheses made in this connection; the aim of this re-examination should be to retain the valuable aspects of these hypotheses and to use them as a basis for their further development and perhaps for the formulation of new hypotheses as well.