The relationship between intrinsic motivation for school learning and school achievement was investigated. An intrinsic motivation inventory was developed to test the hypotheses that intrinsic motivation is differentiated into specific subject areas for school learning; and for specific subjects is positively, significantly, and differentially correlated with achievement in corresponding subject areas. A self-report inventory, measuring pleasure inherent in school learning within subjects, was administered to fourth and seventh graders and correlated with their Stanford Achievement Test scores. Results supported the predictions, suggesting that intrinsic motivation for school learning is differentiated by subject area and that intrinsic motivation within specific subjects is a significant component of school achievement beyond the variance attributable to IQ. The intrinsic motivation inventory proved to be reliable and valid. (Author)