Background: With medical advances since the 1990s, a growing proportion of patients are living for many years with prostate cancer (PCA) and the consequences of its treatment. Objective: The authors investigated the experience of being diagnosed with cancer and the effects of its treatment on patients' partners. Method: The authors conducted an observational, longitudinal study of 103 couples facing the diagnosis of either localized (potentially curable) or metastatic (incurable) PCA at Time 1 and then 6 months later (Time 2). Results: At both Time 1 and Time 2, psychological distress, marital satisfaction, and family functioning were measured in patients and partners; coping was measured in partners only. Partner maladaptive coping patterns of avoidance and self-blame at Time 1 predicted greater partner psychological distress at Time 2, as did "wishful thinking" at Time 2. Discussion: Psychosocial interventions designed to promote adaptive coping in couples facing PCA warrant systematic study.