PURPOSE: To shed light on the nature of online harassment and the extent to which it may be bullying by examining differences in the characteristics of harassed youth, online harassment incidents, and distressing online harassment based on the identity of online harassers (known peer vs. online-only contact). METHODS: A telephone survey of a nationally representative sample of 1500 youth Internet users, ages 10 to 17, conducted between March and June 2005. RESULTS: Nine percent (n = 129) of youth were harassed online in the past year, 43% (n = 56) by known peers and 57% (n = 73) by people they met online and did not know in person (online-only contacts). Most online harassment incidents did not appear to meet the standard definition of bullying used in school-based research and requiring aggression, repetition, and power imbalance. Only 25% of incidents by known peers and 21% by online-only contacts involved both repeated incidents and either distress to targets or adult intervention. CONCLUSIONS: In many cases, the concept of "bullying" or "cyber-bullying" may be inappropriate for online interpersonal offenses. We suggest using "online harassment," with disclaimers that it does not constitute bullying unless it is part of or related to offline bullying. This would include incidents perpetrated by peers that occur entirely online, but arise from school-related events or relationships and have school-related consequences for targets. The Internet provides opportunities for the extension of conventional school bullying to new venues. Those who study conventional school bullying should include online forms of the behavior in research, prevention, and intervention paradigms.