This article assesses gender differences in academic self-concept for a cohort of children born in 1958 (the National Child Development Study). It addresses the question of whether attending single-sex or co-educational schools affected students' perceptions of their own academic abilities (academic self-concept). Academic self-concept was found to be highly gendered, even controlling for prior test scores. Boys had higher self-concepts in mathematics and science, and girls in English. Single-sex schooling reduced the gender gap in self-concept, while selective schooling was linked to lower academic self-concept overall. (Contains 8 tables and 1 note.)