The purpose of this study was to investigate the effects of class-wide assertion skills training on elementary school children's self-esteem and assertive behaviors in their family. In five school hours of home economics, thirty-eight fifth grade children (20 boys and 18 girls) learned the significance of assertion and practiced assertive behaviors for family members. They completed questionnaires about self-esteem, relationship of family members, and assertive behaviors at the beginning and the end of the training.. There were some differences in the assertive behaviors in accordance with different level of relationship of family members. The several assertive behaviors and the self-esteem concerning family and friends increased as the results of training.