This paper presents an algorithm for analyzing social situations within a robot. It contributes a method that allows the robot to use information about the situation to select interactive behaviors. This work is based on interdependence theory, a social psychological theory of interaction and interpersonal situation analysis. Experiments demonstrate the utility of the information provided by the situation analysis algorithm and of the value of this method for guiding robot interaction. It is concluded that the situation analysis algorithm offers a viable, principled, and general approach to explore interactive robotics problems.