The purpose of this research was to investigate the effectiveness of a patient and family pain education program on reducing cancer patients’ and their families’ barriers to (i.e., concerns or misconceptions about) cancer pain management, on increasing patients’ adherence to a prescribed analgesic regimen, and on decreasing pain intensity and pain interference with daily life. An experimental and longitudinal design was used. The experimental group consisted of 31 pairs of cancer outpatients and their family carers, while the control group consisted of 30 patient–family pairs (N = 122). Patients and their family carers in the experimental group simultaneously received a pain management education program. Both groups had pretest data collection and after-test follow-ups on the second and fourth weeks at the outpatient clinics. Comparisons between those two groups were made using the Generalized Estimating Equations (GEE) method. Results revealed that at both the second and fourth weeks, patients and family carers in the experimental group showed a significantly greater reduction in barrier scores than did patients and family carers in the control group. At the second and fourth weeks, patients in the experimental group reported significantly better adherence to a scheduled analgesic regimen than did patients in the control group. In the fourth week, patients in the experimental group reported significantly lower levels of worst pain intensity and pain interference than did patients in the control group. This research provides evidence of the effectiveness of a patient and family pain education program.