Marital outcomes are associated with internalizing and externalizing symptoms; however, the processes by which these domains are associated with marital outcomes are not well understood. This study examined how demand–withdraw (DW) couple communication accounts for the association between symptoms of mental illness and marital distress. A mediational model was tested in a sample of 100 newlywed couples to determine: (a) whether internalizing and externalizing symptoms influenced own and partner's level of DW communication, and (b) whether this communication pattern was associated with relationship outcomes, including lower marital satisfaction and presence of conflict. Results suggested that DW communication had significant effects on both partner's marital outcomes and mediated the association between externalizing symptoms (for husbands) and marital distress.