This article addresses whether students' achievement motivation changes over time, the relationship between changes in motivation and changes in educational attainment, and the between-school differences in these changes and their interrelationships. Also gender differences were studied. Multivariate multilevel latent growth curve analysis was conducted on the data of 4,519 boys and 4,998 girls, belonging to 106 schools. The results showed that achievement motivation was not stable but decreased over time. Boys' motivation decreased more than the motivation of girls. Schools differed with respect to the growth trajectories of achievement motivation as well as of the educational positions. At the student level, the growth trajectory of motivation was not related to the growth trajectory of educational attainment. But we found that at schools in which students more improved their educational position over time, there was a smaller decrease of motivation, as well as the other way around. (Contains 2 tables, 2 figures, and 1 note.)