Two studies examined the role of mindfulness in romantic relationship satisfaction and in responses to relationship stress. Using a longitudinal design, Study 1 found that higher trait mindfulness predicted higher relationship satisfaction and greater capacities to respond constructively to relationship stress. Study 2 replicated and extended these findings. Mindfulness was again shown to relate to relationship satisfaction; then, using a conflict discussion paradigm, trait mindfulness was found to predict lower emotional stress responses and positive pre- and postconflict change in perception of the relationship. State mindfulness was related to better communication quality during the discussion. Both studies indicated that mindfulness may play an influential role in romantic relationship well-being. Discussion highlights future research directions for this new area of inquiry.