Developmental trajectories of two self-concept constructs (self-confidence and importance beliefs) in three domains (academic, social, and self-image) were estimated in a nationally representative sample of approximately 3,500 students with disabilities ages 8 to 17 representing 11 federal disability categories. Students' self-confidence in the three domains declined in elementary school but rebounded in secondary school, whereas their importance beliefs showed linear declines over time. The authors found significant mean differences in self-concept but similarities in the shape of trajectories across disability categories, gender, and race. Students with emotional disturbances or autism had significantly lower self-confidence in the social and self-image domains and lower academic importance beliefs than students with learning disabilities. Girls had significantly higher self-confidence and importance beliefs than boys. Compared to their white peers, Black students had significantly higher self-confidence in all domains, whereas Hispanic students had significantly lower levels of importance beliefs in the social and self-image domains. (Contains 3 tables and 3 figures.)