In this article we present an experimental study (EISI-experiment: experimental induced stress in dyadic interaction), which focuses on a method for analysing individual and dyadic stress-experience and coping as well as its influence on dyadic interaction. The experiment offers a new diagnostic approach to analyse interaction processes under stress. We report the concept of our experimental design and show some first results. The findings suggest that our method is useful for the examination of stress phenomena in close relationships. It allows the investigation of interactional processes and in this context especially of "dyadic coping", a form of stress-management by couples.