The purpose of this study was to explore the effects of an education intervention on nurses’ knowledge, attitudes, and practice in pain assessment and management over 3 months. The education intervention program was designed to change knowledge and influence the attitudes of registered nurses through a values clarification process using a conceptual framework based on a theory of reeducation. Participants in this descriptive, exploratory study were 53 nurses from six oncology units. Data were collected on their knowledge, attitudes, documentation practices, and analgesic choices in defined patient situations. The intervention was effective in changing the knowledge, attitudes, and behaviors of nurses in the study, but the effect was not maintained over time. Study findings suggest that further educational and organizational support is needed for effective practice in pain assessment and management. Further research should explore education programs that will maintain new knowledge over time. In addition, assessment of the effect that new knowledge has on the achievement of improved pain relief for patients should be explored in the future.