This article is a review of the association of individual and marital problems. The focus is on depression, alcohol abuse, anxiety disorders, and the functional psychoses, each of which interact with marital distress in important ways. Although the causal connections between these disorders and marital distress are complex and only particularly understood, the available evidence shows that individuals’ and couples’ problems often exacerbate each other. Consequently, regardless of whether the initial presentation is individual or couple focused, there is routinely a need to assess both individual and relationship functioning. Couples therapy, and in particular behavioral couples therapy (BCT), is an important element of effective treatment of depression, alcohol abuse, anxiety disorders, and the functional psychoses. The integration of couple and individual therapy presents a number of clinical challenges, and in concluding this article the authors provide guidelines for managing these challenges.