Abstract
The present study focuses not only on the impact of students' achievement motivation, but also on the influence of achievement motivation of fellow students on status and growth in language and math achievement across Grades 7 and 8. The achievement motivation of schoolmates may create a learning environment that facilitates or impedes learning above and beyond what would be expected on the basis of the individual student's achievement motivation, intelligence and background characteristics. Data from the LOSO-project, a longitudinal study in secondary education, have been analysed using multilevel linear growth curve modeling. It turns out that the effect of achievement motivation, both of individuals and in groups, should not be neglected in explanations of individual progress in achievement, even when ability and background characteristics such as the socio-economic status, age, sex and home language have been controlled for. In addition, the data suggest that especially boys with poor achievement motivation at the start of secondary education are at risk of falling behind with regard to language achievement in the subsequent years.