Individuals with chronic pain may experience negative responses from spouse, family, and friends. Responses such as overt criticism and hostility may be associated with worsening pain and function for chronic pain sufferers. We used a laboratory procedure to evaluate whether variability in spouse criticism/hostility exhibited toward chronic low back pain (CLBP) patients during a conflictual discussion predicted variability in patient pain and function during a subsequent pain-induction task. Chronic low back pain patients (n = 71) and their spouses (n = 71) participated in a 10-minute discussion followed by the patient undergoing a 10-minute structured pain behavior task (SPBT). Spouse criticism/hostility perceived by patients and patient Beck Depression Inventory-II (BDI) scores correlated significantly and positively with pain intensity during the SPBT, whereas perceived spouse hostility, patient BDI scores, and spouse trait hostility correlated significantly and positively with observed pain behaviors during the SPBT. Spouse criticism/hostility coded by raters from video recordings interacted significantly with patient BDI scores, such that observed spouse criticism/hostility was related significantly and positively with pain behaviors only for patients with high BDI scores. Patient sex interacted significantly with observed spouse criticism/hostility, such that observed spouse criticism/hostility was related significantly and positively with pain behaviors only for female patients. Results support the hypothesis that spouse criticism and hostility—actually expressed or perceived—may worsen CLBP patient symptoms. Further, women patients and patients high in depressive symptoms appeared most vulnerable to spouse criticism/hostility. Thus, negative marital communication patterns may be appropriate targets for intervention, especially among these 2 at risk groups.