摘要:Background: Different biological and environmental factors may play roles in the development of self-concept. Many studies have focused on gender or age differences in self-concept separately. Objective: The current study aimed at examining the effects of grade, gender and their interaction on the development of four self-concept dimensions (appearance, school, parent-relations, and peer-relations) among Omani adolescents. Methods: The study sample was 651 middle and high school students from two districts in Oman. The students were enrolled in grades 7, 9 and 11. The study utilized the Self-Description Questionnaire (SDQ-1, Marsh, 1988) to assess students' levels in the self-concepts dimensions. The study adopted the descriptive design using Two Way Multivariate Analysis of Variance. Results: The study results demonstrated that grade and gender interaction affected appearance self-concept development; however, this interaction had no effects on the other dimensions. Moreover, gender and grade differences were found in some dimensions of self-concept. Conclusion: The study suggested that the effects of grade level and gender varied based on the self-concept dimensions. Adolescents' self-concept should be given a careful attention for its important role in providing healthy outcomes.