This paper presents the positivist and constructivist theory and practice of focus groups. We pointed out to the paradigmatic differences in notional attributes of focus groups, as well as to the historic circumstances of their appearance. We analyzed the practice of focus groups in positivist and constructivist paradigm, through the combination of two interpretative frameworks. The fist level of analysis is Foucault’s genealogy which enables to observe the research as a social technology of disciplining and producing the discourse of subjectivity. Goffman’s metaphor of social interaction as a "scene" where the rituals of its maintenance and disturbance constantly take place is the second level of analysis of practice of focus groups. These two levels of analysis are the tool for understanding the complex relation between the way in which social practice of research is constituted and the knowledge it produces.