The aim of this article is to sum up the principles of social constructivism as a foundation of all theories of discourse, and to identify key characteristics of main discursive theories, as well as perspectives of their use in the research of inequalities. We explore key theories of discourse (critical discourse analysis and theoretical frameworks based on works of Foucault and Laclau and Mouffe), and application of methodological approaches of discourse analysis stemming out from these theories, in current social research. All discourse theories are founded on principles of social constructivism: social construction of knowledge, existence of multiple variants of knowledge, simultaneous construction and reproduction of social reality in the process of social relations, and an idea that subjects construct knowledge inside of discourse, while discourse in turn constructs social reality. Characteristics of discourse theories were identified around criteria of the degree of inclusivity of discourse, functions of discourse, stability of discursive structure, degree of subjects’ agency. Approaches to discourse analysis that stem from the works of Foucault and Laclau and Mouffe suggest a strong link between theory and methodology, with research methods less clearly defined. Critical discourse analysis fills this gap in methodological developments. In particular, for social research purposes, Norman Fairclough’s approach to critical discourse analysis is widely used, looking at discourse as a social practice, a type of speech, typical of a certain area of knowledge, and as an articulation of a person’s or a social group’s lived experience that stems from their structural position. Fairclough’s analytical model consists of three levels: a detailed linguistic analysis of the text, analysis of daily routine practices and ways in which people construct social order, and macrosociological analysis of the social practice. The article ends with discussion of examples and common areas of discourse analysis usage in research of structural social inequalities.