Individuals who aggress against others have been described both as having overall low self-concept and as having high, inflated self-concept. The conceptualization of self-concept as domain specific provides an alternate means to resolving this controversy. In this study, 223 middle school students completed self-report measures assessing self-concept across six domains as well as engagement in peer aggression, including cyber aggression. Hierarchical regression analyses revealed that individuals who reported engaging in higher levels of traditional and cyber peer aggression reported significantly lower self-concept in the domains of behavioral adjustment, intellectual and school status, and happiness and satisfaction. Higher levels of traditional and cyber peer aggression were not significantly related to self-concept in the domains of popularity, physical appearance and attributes, and freedom from anxiety. Implications for research and practice are discussed.