In many types of activities, communicative and material activities are so intertwined that the one cannot be understood without taking the other into account. This is true of maritime and hospital work that are used as examples in the paper. The spatial context of the activity is also important: what you can do depends upon where you are. Finally, human and automatic machinery alternate in filling certain roles in the activity: sometime the officer maintains the course, sometimes the autopilot. Such activities require us to rethink the traditional oppositions between communication and instrumental actions, between human and non-human participants, and between an activity and its spatio-temporal context. The advent of pervasive technologies, where active or passive systems become embedded in our working and living spaces, from where they offer their services to us, puts the need to reconsider these basic oppositions high on the research agenda. This paper presents a consistent framewor...