Background: Pain is commonly regarded as one of the most unpleasant experiences that people fear yet will have to deal with at some point in their lives, with variable intensity and duration. Aim: Determine the effect of an educational program on nurses' performance levels regarding pain assessment and management. Design: A quasi-experimental one-group, pre- and post-test intervention design was used to conduct this study. Setting: The present study was conducted at the inpatient medical and surgical department at Al-Zarqa Governmental Hospital, Jordan. Subject: 106 male/female nurses volunteered to participate in the study, providing direct nursing care for patients at medical and surgical wards. Tools: Two adopted tools were used by the researcher to conduct this study, a nurses' knowledge about pain assessment and management questionnaire and a nurses' practices observational checklist. Results: The study found that more than two thirds of the studied nurses were female and had a Bachelor of Science in Nursing. They had 2–5 years of experience, and 88.7% had not attended any educational sessions on pain assessment and management. There was a significant difference in the mean score of knowledge between the pre-educational program and post received pain education as measures by the knowledge questionnaire P<0.001. After implementation of the education program, all dimensions of nurses' practices significantly differ, with a high correlation between knowledge and practices pre-, post-, and immediately after the implementation of the program. Conclusion: More than half of the studied nurses had a good total level of knowledge and a satisfactory level of practice regarding pain assessment and management after the implementation of the educational program. Recommendations: Nurses should be encouraged to attend pain assessment and management training.