Accumulating research has shown that conflictual romantic relationships are powerful instigators of stress, as measured by subjective reports, hormonal and cardiovascular reactivity, and immune functioning in both laboratory contexts and naturalistic settings. Significantly, couple conflict appears to increase cortisol levels via hypothalamic-pituitary-adrenal axis activation, such that individuals under chronic relationship stress may have increased health risks associated with immune dysfunction. Theory and incipient evidence indicates that mindfulness may play a beneficial role in ameliorating relationship stress. Trait mindfulness has been associated with relationship satisfaction and lower anxiety, hostility, and relationship discontent after couple conflict. Mindfulness training has been shown to enhance relationship satisfaction in non-distressed couples. There is growing evidence that mindfulness training is associated with lower stress-related subjective, physiological, and immune outcomes. Together this research provides support for the proposed study, designed to experimentally examine the effect of mindfulness training on stress indicators before and after couple conflict interactions. This study will extend initial research on the role of mindfulness in enhancing romantic relationship functioning, and is expected to have research implications for both normative and clinical couple populations (e.g., those affected by domestic violence). This study will include significant methodological improvements over past correlational and self-report-based research in this area.