This study aimed to investigate associations between reactive and proactive aggression and peer relations and peer deviance among high school girls. A total of 442 high school students participated in this study. Reactive-Proactive Aggression Questionnaire, the Peer Relations Scale, and the Peer Deviance Scale were used to collect data. Results revealed that self-disclosure, loyalty, mild deviance, and serious deviance were significantly and positively correlated with both reactive and proactive aggression. Findings also indicated that self-disclosure, loyalty, and mild deviance among peers were significant predictors of reactive aggression, while loyalty and mild deviance were significant predictors of proactive aggression.