Latent class analysis was used to examine whether patterns of bystander responses varied as a function of both student- and school-level characteristics. Data from 18,863 high school students from 58 schools who "ever witnessed bullying" were used to identify five latent classes of bystander behavior. Three of the classes identified paralleled commonly used researcher-identified categories ("Passive" = 9.7%, "Defender" = 20.4%, and "Contributor" = 3.4%), whereas we also identified two patterns of bystander responses that had not been previously characterized ("Limited" = 64.8% and "Inconsistent" = 1.7%). Multilevel logistic regression models were then used to examine student- and school-level characteristics that differentiate those in the defender class from other bystander classes. Youth in the defender class were more likely to believe that other students intervene with bullying, and they felt a greater connection with school staff as compared to youth in all other bystander classes. Further, gender, normative beliefs about retaliation, and bullying involvement were associated with class membership. Findings indicated that defending bystander responses are relatively low and suggested that school-level contextual factors, youth perceptions of others' bystander behavior, and bullying involvement all inform our understanding of adolescent bystander behavior.