This data brief introduces the Friendship and Identity in School (FIS) dataset. The FIS data are school-based longitudinal social network data, which have become increasingly important in recent years. Including information on 2,500 adolescents in nine secondary schools in the German federal state of North Rhine-Westphalia, the FIS data have four important key fea-tures that make them uniquely suited for studying the co-evolution of friendship networks and group identities or other time-varying individual characteristics. Specifically, the data include (i) fine-grained multi-dimensional measures of youth’ ethnic, national, and religious identities, (ii) comparatively large social networks that span multiple classrooms, (iii) up to six waves over four and a half years, and (iv) an ethnoreligiously diverse sample. Besides friendship and identity, the data include other network dimensions such as romantic relations or dislike as well as repeated measurements of various individual attributes ranging from perceived dis-crimination over intergroup attitudes and religion to leisure time activities and students’ per-ceptions of parents’ identities and attitudes. In combination, the FIS data provide rich longi-tudinal information that allows researchers to study the development, change, and interplay of youth’ group identities and friendship networks as well as broader questions concerning inter-group relations, network formation, and peer influence.
