This preface to the translation of Harvey Sacks, Emmanuel Schegloff, and Gail Jefferson’s paper “A Simplest Systematics for the Organization of Turn-Taking for Conversation” discusses the conceptual and methodological foundations of conversation analysis. It shows that conversation analysis, which embodies the program of primitive natural social science formulated by Harvey Sachs, offers a revolutionary approach to the study of social phenomena, based on detailed analysis of naturally occurring everyday interactions. While remaining closely related to Harold Garfinkel’s ethnomethodology, conversation analysis shows how careful and detailed can be sociological descriptions that involve the discovery of general mechanisms (“machinery”) of the production of single events of conversation or any other social practice. This approach, however, risks losing the original purpose of studying the local concerted work of mutual understanding by the participants in social situations. The accumulation of the descriptions of general mechanisms of interactions’ production and perception brings the tendency of formalization into conversation analysis: analysts tend to collect the instances and properties of already known “interactional techniques.” The article considers the importance of “Simplest Systematics" in terms of the development of original program of conversation analysis, and discusses the peculiarities of translation of conversation analysis’s key terms into Russian.