T HIS ESSAY IS part of a continuing investigation of the ways in which users-commonly assumed to be passive and guided by established rules-operate. The point is not so much to discuss this elusive yet fundamental subject as to make such a d iscussion possible; that is, by means of inquiries and hypotheses, to indicate pathways for further res earch. This goal will be achieved if everyday practices, "ways of operating" or doing things, no longer appear as merely the o bscure background of social activity, and if a body of theoretical questions, methods, categories, and perspectives, by penetrating this obscurity, make it possible to articulate them.