Modern society is highly complex and differentiated. Sociological theories help us to make sense of this complexity, to understand and penetrate realities at all levels of social aggregation ? at the micro-level of individual interaction and of small collective units (such as the family), at the meso-level of organizations and intermediate institutions (such as business firms) and at the macro-level of society's basic structure. They enlighten us about hidden forces, principles and interests which shape our daily lives and the reproduction of social structures. This module aims to demonstrate the usefulness and limitations of different theories both as tools of analysis and as concrete guides to social practices.