Much research has been done on the personality characteristics of children identified as gifted on general intelligence measures. Past research, however, has suggested that personality may vary as a function of the specific area of giftedness, the absolute level of giftedness, and the sex of the adolescent. Mathematical ability is of particular interest, since this ability area is usually stereotyped as being more appropriate for males, and may have differential affect on the personalities of gifted boys and girls. Therefore, the present study investigated the self-esteem and self-concepts of boys and girls (N = 216) who were either highly gifted, able, or average mathematical ability. Thirty-six students of each type completed the Adjective Check List. In regard to self-esteem, level of mathematical ability had no effect on the self-esteem of boys, but did for girls. Furthermore, both sex of S and level of ability had an effect on the content of the self-descriptions.