Despite its frequent appearances in sociological textbooks, dictionaries and theoretical opuses, ethnomethodology is still one of the most misunderstood and undervalued domains of sociological inquiry. This is particularly evident in the case of the central sociological question: social order. Harold Garfinkel, the founder of ethnomethodology, provided a unique answer to the question of order. His answer emphasized a contingent, situated character of constitutive practices of local order production. Initially a response to Talcott Parsons’ question about the conditions of the stability of social order, Garfinkel’s conception of constitutive order was later radicalized and used as the foundation of the programme of empirical ethnomethodological studies. To properly understand the radical character of the conception and programme, it is necessary to reveal the core elements of it and to separate them from the historically changed components.