Arranging to do things with others

Much of what we do we do with other people. We conduct business, gossip, play games, and take classes with others, both in person and through computers. Joint activities like these axe advanced through sequences of brief joint actions, The problem is this. It takes delicate coordination against the common ground of the participants to initiate such actions. Person A has to arrange for person B (1) to commit to taking part (2) in a particular joint action (3) in a particular role (4) at a particular time and place. I will argue that people have principled ways of solving this problem, and that designers can and should leverage these principles when supporting these activities through computers and other technologies.