Previous research on married couples has demonstrated the direct influence of mental health on marital quality. However, the processes that mediate and moderate the associations between depressive symptoms and marital quality are less understood. Using a social functionalist perspective, this study examined whether depressive symptoms were associated with marital quality directly or through couple interactions, and whether perceptions of ones partners emotional expression buffer the negative association between depressive symptoms and couple interactions. Based on data collected from a sample of 512 married individuals analyses supported the indirect association between depressive symptoms and marital quality such that married individuals who reported more frequent depressive symptoms were more likely to report less frequent positive couple interactions and consequently lower marital quality. As well, the results indicated that partner emotional expression moderates this association. This study facilitates understanding the mechanisms through which mental health is associated with marital quality.