Individuals with a psychiatric disorder are significantly more likely to have a spouse with a clinical diagnosis—marital concordance. We used a community sample of 304 couples concordant for either major depressive disorder (MDD) or substance use disorders (SUDs) to examine the relationship between marital functioning and gendered patterns of mental health diagnosis onset. For SUD concordance, couples in which wives onset before husbands—despite typical later onset for men—reported lower levels of marital satisfaction compared with couples in which the husband onset first. For MDD concordance, couples in which husbands onset with depression before wives—despite typical later onset for men—reported lower levels of marital satisfaction. These results suggest that for couples concordant for mental diagnoses, it is most problematic for marital functioning for one partner to have an atypically early onset. Implications for treatment targets in marital therapy are discussed.