BACKGROUND: Individual achievement goals are influenced by the learning context, such as the classroom. In this social space, social norms emerge and shape motivation and behaviour. Classroom goal structures reflect injunctive norms (what is considered acceptable) and influence individual achievement goals. The role that descriptive norms (what others typically do or think) play in individual achievement goals is unclear. We propose that peer achievement goals reflect descriptive norms and additionally influence individual achievement goals. AIMS: We aim to better understand contextual influences on individual student motivation by applying a social norms framework to study changes in individual achievement goals and acknowledge the role of peers. SAMPLE AND METHODS: We used longitudinal data from 4189 students from 169 classes at two time points after the transition to secondary school. RESULTS: We calculated multilevel models to predict changes in individual mastery-, performance-approach, and performance-avoidance goals. As Level-2 predictors, class-level classroom goal structures represented injunctive norms, while peer achievement goals represented descriptive norms. Individual achievement goals and individual-level classroom goal structures were added on Level 1. Class-level classroom goal structures related to changes in individual achievement goals only if peer achievement goals were not added. If added on the classroom level, peer achievement goals remained as a single Level-2 predictor of changes in individual achievement goals. CONCLUSION: We demonstrated the key role that descriptive norms (reflected by peer achievement goals) play in individual achievement goals. The role of injunctive norms needs to be investigated further to enhance our understanding of how social norms shape individual student motivation.