The use of grades to motivate constitutes an unresolved theoretical controversy. In 2 experiments carried out with different age groups and academic tracks, a standard-grade condition was compared with a condition in which differential scoring engendered higher grades and with a no-grade condition. The relative power of task performance and task autonomy to explain differences in subsequent intrinsic motivation (self-report task interest and continuing motivation for the task) was assessed. Results show that, compared with the standard-grade condition, both high-grade and no-grade conditions enhanced the 2 forms of subsequent intrinsic motivation. However, although task performance explained higher levels of task interest in the high-grade condition, it failed to explain higher levels of continuing motivation for the task. Task autonomy, conversely, explained the higher levels of both task interest and continuing motivation for the task experienced in the nongraded condition. Results are discussed in the light of an integrative model that differentiates the mediational role of task performance and autonomy, 2 traditional major explanations of the link between grades and intrinsic motivation. (Contains 11 tables, 3 figures and 9 footnotes.)