How can Internet use in the domestic sphere be analysed empirically without over-determining the status of family categories? How can 'familiarization'? with the Net be examined on the basis of rigorous study of courses of action? From video recordings of ordinary uses of Internet in the home, the authors have selected specific sequences attesting to individual practices oriented towards membership of the family collective. This study shows how, in the observed situations, through their Internet-related activities, family members place themselves in the different categorical positions of the 'family'? device. The authors have thus developed a situated approach to categorization, in which they incorporate the ecological dimension of the conversational dynamic of activities.