['Breast cancer diagnosis and treatment negatively affect quality of life in survivors and their supportive partners. The purpose of this investigation was to assess the degree of dyadic interdependence in psychological and physical symptom distress in dyads adjusting to breast cancer.', 'Participants were 49 breast cancer survivors and their partners, who were spouses, other family members, or friends of the survivor. Psychological distress (depression, anxiety, and negative affect) and physical symptom distress were measured at three points in time, each separated by eight weeks.', 'Survivors and partners exhibited significant interdependence in psychological and physical symptom distress over the four-month course of the investigation. This was evident in longitudinal partner effects in actor-partner interdependence models as well as in significant T1→T3 indirect effects mediated by partner distress.'] Are psychological and physical distress interdependent in breast cancer survivors and their partners?