The problem of social class is one of the central for sociology and, at the same time, constantly debated - regarding both the definition of the concept of class and its role in social theory and significance for sociological analysis of post-industrial society. The book sets out the theoretical foundations of six alternative approaches to class analysis in modern sociology, which are represented by giants of relevant areas. In conclusion, E. O. Wright (the initiator and editor of this collective monograph) offers a conceptual generalization of the analyzed approaches based on the wording of six nodal questions, the answers to which determine the differences between the corresponding class concepts.