Using an accelerated longitudinal design, we investigated developmental changes in young peoples’ evaluations of sexual harassment (SH) and how young peoples’ own experiences with harassment, their perceptions of teacher intervention, as well as how gender and sexual orientation related to their judgments. This study documented significant changes in adolescents’ evaluations of peer‐based SH from grades 7 to 10. Overall, there was a significant decrease in the extent to which youth judged SH to be wrong as they progressed through school. Yet, there was also significant variability across youth in their initial judgments at grade 7 and the extent to which their judgments changed over time. Youth judged SH to be less wrong at occasions when they reported engaging in this behavior more frequently. Conversely, youth judged SH to be more wrong at occasions where they saw teachers intervene. In grade 7, girls, youth more frequently reporting seeing teachers intervene, and youth reporting less SH perpetration judged SH as more wrong than boys, those reporting less teacher intervention, and those reporting higher perpetration, respectively. Perceptions of teacher intervention attenuated the grade‐related declines in judgments of wrongness. The results of this study have important implications for research and policy related to SH among adolescents.