Background: The Aggressive Student Culture Scale (ASCS) is a survey designed to measure the extent to which New Zealand (NZ) students experience aggressive behaviours within the school environment. The aim of this study is to assess the psychometric properties of the ASCS in the multidisciplinary "Growing Up in NZ" longitudinal study. Methods: We used data from 4938 children from the "Growing Up in NZ" study to examine the psychometric properties of ASCS for 8-year-old children. Confirmatory factor analysis was conducted, and measurement invariance was tested across sex, ethnicity, and deprivation levels. Results: The ASCS tool comprises a single latent factor--aggressive student behaviour. The ASCS provides an adequate and satisfactory measure for student aggression experiences. Full measurement invariance was supported for child's sex, but only configural invariance was confirmed across ethnicity and area-level deprivation. Males reported higher levels of aggressive experiences than females. Conclusions: The one-factor model structure offers an excellent fit to our data with good internal consistency. Comparisons across sex are valid; however, direct comparisons across ethnicity and deprivation levels should be approached with caution. We recommend replication studies and encourage further research involving participants from different age groups to better understand the factor structure across diverse demographic variables.