The current study examines normative developmental trajectories of school and cybervictimization across 3 years of high school and tests whether school and cybervictimization experiences predict increases in loneliness at school or whether loneliness at school increases the risk of victimization. Gender differences are also explored. Data were drawn from a longitudinal sample of 4,339 ethnically diverse U.S. adolescents (M
age = 15.02) who completed surveys in 9th, 10th, and 11th grades. Whereas school victimization decreased, cybervictimization increased across high school. School‐based victimization and loneliness were bidirectionally related across time (controlling for cybervictimization), but cybervictimization and loneliness were not related (controlling for school victimization). The findings provide a nuanced account of the associations between school and cybervictimization with feelings of isolation at school.