Despite many works in CSCW, groupware, workflow systems and social networks, computer support for human-to-human interactions is still insufficient, especially support for agility, i.e. the capability of a group of human beings, collaborators, to rapidly and cost efficiently adapt the way they interact to changes. In this paper, requirements for computer support for agile H2H interactions are presented. Next, the concept of social protocol is proposed as a novel model supporting agile H2H interactions. A social protocol consists of an extended social network and a workflow model.