In order to evaluate the hypothesis that there is no difference in the self-concept of adolescent students from single sex and co- educational high schools, the investigator conducted a study on 60 subjects (30 boys and 30 girls) out of which 30 subjects were from single sex schools and remaining were from the co- educational school. The measurement was done using the Self-concept Rating Checklist by Dr. Pratibha Deo which contains 90 adjectives describing a person’s self-concept. The result shows that adolescent students from co- educational schools have a better self-concept as compared to the adolescent students from single sex schools. When the various dimensions were analyzed, it was found that the boys from co- educational schools had better aesthetic and character dimensions while the girls from the co- educational schools were found to be better in social and intellectual dimensions.