The efficacy of problem-solving therapy (PST) to reduce psychological distress was assessed among a sample of 132 adult cancer patients. A second condition provided PST for both the patient and a significant other. At posttreatment, all participants receiving PST fared significantly better than waiting list control patients. Further, improvements in problem solving were found to correlate significantly with improvements in psychological distress and overall quality of life. No differences in symptom reduction were identified between the 2 treatment protocols. At a 6-month follow-up, however, patients who received PST along with their significant other reported lower levels of psychological distress as compared with members of the PST-alone condition on approximately half of the outcome measures. These effects were further maintained 1-year posttreatment.