Supportive relationships enhance mood and patient adjustment (Stanton, Revenson, & Tennen, 2007). However, unsupportive or critical relationships lead to relapse and poor outcomes in both mental and physical disorders (Wearden et al., 2000). The converse is also true. Patient adjustment, specifically patient mood, influences the amount of support or criticism given by spouses (Gotlib & Beach, 1995; Revenson, 1994). Both spouses in couples with Chronic Low Back Pain (CLBP) have higher than average rates of depression (Schwartz & Ehde, 2000) and marital discord (Leonard, Cano, & Johansen, 2006). Therefore, relational models describing how depression and unsupportive behavior develop in both spouses are necessary for understanding problems that these couples face. We examined bidirectional relationships between spousal affect and behavior in a sample of 105 married couples with one spouse experiencing CLBP. Ecological momentary assessment (EMA; Shiffman, Stone, & Hufford, 2008) with electronic diaries was used to obtain reports of patient and spouse affect as well as criticism and support for five times a day over 2 weeks. Hierarchical linear modeling was used to investigate both concurrent and lagged associations between behavior (criticism and support) and depressed affect. As hypothesized, both within- and cross-spouse associations between criticism and depressed affect were significant when both criticism and depressed affect were measured at the same time point. Contrary to expectations, only some within- and cross-spouse associations between support and depressed affect were significant at the same time point. Results from lagged models of criticism and depressed affect suggested that there are bidirectional relationships between spouse criticism and spouse depressed affect; as well, they highlighted the role of spouse depressed affect in predicting patient criticism. Lagged models of support were similar to those for criticism. These results highlight the implications of being critical and providing support as well as the role of spouse affect in generating marital conflict. Results also call for the importance of expanding theory and interventions to address not only patient affect but also spouse depressed affect as it may be a stress generating vehicle leading to both spouse and patient criticism and support.