A large body of research in the field of marital interaction has focused on communication and interaction patterns in problem-solving situations or conflict discussions. On the other hand, the influence of stress on marital interaction was mainly neglected. However, stress and coping are assumed to be important variables in the context of marriage and their analysis may contribute to a better understanding of marital tension and dissatisfaction over time. In the current study we investigated the influence of coping as a moderator variable between self-perceived stress (self-report-data) and the open interaction behavior (systematic observation) of intimate partners in a stressful situation (EISI-experiment: Experimentally induced stress in dyadic interactions). As the results show, marital interaction is more negative under stress conditions. On the other hand, the the practice of adequate intrapsychic coping has a positive influence on marital interaction and helps decrease expressed negativity towards the partner under stress. Among dysfunctional coping behaviors all kinds of intrapsychic blaming revealed the most unfavorable effects on marital interaction. It is noteworthy that especially nonverbal and paraverbal negative interaction behaviors were more often practiced by the group of inadequate copers. Tension-reduction and reframing, on the other hand, gave evidence for a positive moderator effect between stress and dyadic interaction. Persons who coped this way were less negative with their partner even under stress than the group showing no or little performance of these coping styles. Our findings suggest that cognitive variables (such as intrapsychic coping) have an important impact on marital interaction.