In two large confirmatory factor analyses (Ns = 11,029 and 1,397) of Self-Description Questionnaire (SDQ-I) responses, we examined how the separation of competency and affect components of reading, math, and school self-concept varies across ages 7-13. The SDQ-I factor structure was well defined with factor loadings invariant over both longitudinal and cross-sectional age comparisons. ... [Show full abstract] Correlations among reading, math, and school self-concepts systematically decreased with age, but correlations between competency and affect within each domain remained consistently large. With age and development, students more clearly distinguish between different academic self-concept domains, but the relation between intrinsic liking and competency remains strong. We tentatively recommend that researchers distinguish between competency and affect components of academic self-concept, qualified by the need to evaluate further the construct validity of this separation in relation to additional external validity criteria.