Past research on family members as psychosocial stressors leading to increased symptom distress has been mostly limited to psychiatric populations and has been problem-focused. The current study used behavioral observations and partner reports to examine the relationship between positive and negative partner behavior and individual symptom distress, mediated by perceived criticism, in 96 clinical couples. Results of structural equation modeling showed that male negative behavior had a positive relationship with female symptom severity mediated by perceived criticism. Female negative behavior had a negative relationship with male symptom severity, not mediated by perceived criticism. Warmth displayed no significant relationship with perceived criticism or symptom severity for either gender. Recommendations for future research include examining the role of power in the relationship between negative partner behavior and symptom severity and assessing the ratio between positive and negative behaviors rather than as separate variables. Replication of these results is warranted.