The present investigation evaluated relations between bullying, victimisation, multiple dimenstions of self-concept, sex and age over two occasions for a large sample of students (N =3445) from six high schools in Year 7 to 11. In Study 1, there was strong psychometric support (confirmatory factor analysis and reliability) for two new instruments; a new short version of the widely used Self Description Questionnaire II (SDQII-S) that measures 11 different components of self-concept and Adolescent Peer Relations Instrument that measures three Bully factors (Physical, Verbal, Relational) and the corresponding three Victim factors. In Study 2, males used all three types of bullying (Physical, Verbal, Relational) and experienced two types of victimisation (Physical and Verbal) significantly more than females. Whereas levels of victimisation and bullying both increased during early high school years, vitimisation tended to decrease during subsequent high school years whereas bullying did not. In Study 3, longitudinal causal models indicated that victimisation and bullying are positively correlated and multually reinforcing constructs. Bullying leads to continued bullying but also becoming a victim, whereas being a victim leads to continued victimisation but also becoming a bully. Victim and low social self-concepts had multually reinforcing negative effects. Contrary to predictions, however, increased bullying did not enhance subsequent social self-concepts. The results suggest that increased social consciousness about the negative effects of bullying may have undermined the ability of bullies to use anti-social bullying tactics to enhance their self-concepts.