Although prior research has indicated that peer norms for aggression enhance the spread of aggression in classrooms, it is unclear to date how these norms relate to students’ classroom climate perceptions and school adjustment. Aggressive descriptive norms reflect the average aggression of all students in classrooms, whereas aggressive popularity norms represent the extent to which aggressive behavior relates to popularity among peers. This study examined the role of aggressive descriptive and popularity norms in the classroom climate perceptions (cooperation, conflict, cohesion, isolation) and school adjustment (feelings of belonging; social, academic, and general self-esteem) of popular, well-liked, and victimized children. Self-reported and peer-nominated data were obtained from 1,511 children (Mage = 10.60 years, SD = .50; 47.2% girls) from 58 fifth-grade classrooms. The results indicated that aggressive descriptive and popularity norms both matter in elementary school, but in diverging ways. Specifically, aggressive descriptive norms – rather than popularity norms – contributed to negative classroom climate perceptions irrespective of students’ social position. Next, whereas descriptive norms contributed to between-classroom variations in some aspects of school adjustment, aggressive popularity norms related to increased school maladjustment for popular and victimized children specifically. In sum, aggressive descriptive norms and popularity norms matter in complementary ways for children’s perceptions of their adjustment in elementary education.All information about the content of the files is described in 'read me_Laninga-Wijnen et al_2021.pdf'. This file also contains information about the recruitment, participants and data collection. Data and the syntax for the analyses as presented in the paper are also stored.