Whilst literature on traditional bullying continues to grow, a paucity of research exists regarding its newest form: cyber bullying. The present study consisted of a sample of Australian secondary students (N = 803) and aimed to identify the underlying structure of cyber bullying. A previously validated measure of traditional bullying, the Adolescent Peer Relations Instrument - Bully and Target (APRI-BT; Parada, 2000), was extended to include cyber bully and target behaviours. Reliability analyses and Confirmatory Factor Analyses (CFA) demonstrated that the newly extended measure of traditional and cyber bullying behaviours was psychometrically sound. It was concluded that the current investigation provided a firm understanding of the nature and structure of cyber bullying, thus forming a sound base from which to conduct future bullying research. Moreover, potential limitations of the present investigation, and implications for theory, research, and practice were discussed.