While the origins and consequences of populist attitudes in adults are being studied extensively, it is still unknown when populist attitudes might emerge in a person’s life. Drawing on the existing literature on political socialization, we focus on populist attitudes during adolescence and explore the contributing role of negative relationships with parents, peers, and teachers. We provide the first comprehensive analysis of populist attitudes among a representative sample of children aged 12 to 18 (mean: 14.66 years) using a unique dataset gathered through interviews conducted in schools in Austria, Germany, and Switzerland (n=3,123). Our findings reveal a strong association between perceived unjust teacher behavior and the level of populist attitudes in adolescents, while the connection of peers and parents with populist attitudes appears to be limited. Further analyses using panel data from the UK support these findings.