Purpose: The purpose of this study was to develop and evaluate the effect of a cultural competency promotion program for nurses in obstetrics-gynecology and pediatrics. Methods: The cultural competency promotion program was developed through the Analysis, Design, Development, Implementation, and Evaluation (ADDIE) steps. In this quasi-experimental study, 30 nurses in obstetrics-gynecology and pediatrics were assigned to the experimental group and 34 nurses were assigned to the control group. The experimental group received this program once a week for four weeks and each class lasted one hour. Data were analyzed using descriptive statistics, t-test, X 2-test and Fisher's exact test with the IBM SPSS Statistics version 21.0 program. Results: After attending the program, cultural competency (t = 8.30, p < .001) increased significantly in the experimental group compared to the control group. There were also significant differences between two groups in cultural awareness (t = 7.53, p < .001), cultural attitude (t = 6.41, p < .001), and cultural knowledge & skills (t = 7.79, p < .001) as components of cultural competency. Conclusion: The results of this study indicate that this cultural competency program is effective and efficient for nurses in obstetrics-gynecol-ogy and pediatrics and can help nurses provide appropriate multicultural nursing care in multicultural society. This is an Open Access article distributed under the terms of the Creative Commons Attribution Non-Commercial License (http://creativecommons.org/licenses/by-nc/3.0/) which permits unrestricted non-commercial use, distribution, and reproduction in any medium, provided the original work is properly cited.