The aim of this study was to establish whether the relationship between self-concept of academic ability and academic achievement correlated more strongly than the relationship between global self-concept and academic achievement among high school students. Data on these variables were collected from 229 tenth-grade students in the U.S. Pacific Northwest public school district. The results indicate that global self-concept and self-concept of academic ability correlate positively with academic achievement, but the relationship between self-concept of academic ability and academic achievement correlated more strongly than the relationship between global self-concept and academic achievement. The results suggest that educational intervention strategies geared to raising academic achievement would probably be more likely to succeed if they were to focus on enhancement of the self-concept of academic ability rather than global self-concept.