Using data from 2413 Dutch first-year secondary school students (M age. = 13.27, SD age. = 0.51, 49.0% boys), this study investigated as to what extent students who according to their self-reports had not been victimized (referred to as reporters) gave victimization nominations to classmates who according to their self-reports had been victimized (referred to as receivers). Using a dyadic approach, characteristics of the reporter-receiver dyad (i.e., gender similarity) and of the reporter (i.e., reporters' behavior during bullying episodes) that were possibly associated with reporter-receiver agreement were investigated. Descriptive analyses suggested that numerous students who were self-reported victims were not perceived as victimized by their non-victimized classmates. Three-level logistic regression models (reporter-receiver dyads nested in reporters within classrooms) demonstrated greater reporter-receiver agreement in same-gender dyads, especially when the reporter and the receiver were boys. Furthermore, reporters who behaved as outsiders during bullying episodes (i.e., reporters who actively shied away from the bullying) were less likely to agree on the receiver's self-reported victimization, and in contrast, reporters who behaved as defenders (i.e., reporters who helped and supported victims) were more likely to agree on the victimization. Moreover, the results demonstrated that reporters gave fewer victimization nominations to receivers who reported they had been victimized sometimes than to receivers who reported they had been victimized often/very often. Finally, this study suggested that reporter-receiver agreement may not only depend on characteristics of the reporter-receiver dyad and of the reporter, but on classroom characteristics as well (e.g., the number of students in the classroom).