There were two primary areas of focus for this thesis. The first was to identify what changes had occurred in bullying behaviour in Australian secondary schools compared to findings of those of the previous decade. Evaluating this involved a cross sectional study of 618 students from Year 8 through to Year 12. The main findings were in line with previous research in that boys were still more likely to report being bullied, although group bullying had increased for boys. Younger students were more likely than older students to report bullying. There was a meaningful increase in the percentage of students feeling unsafe at school from bullying. Male and female students were equally as likely to be a participant in group bullying. However, the reasons for bullying differed across year levels. The second component of this thesis was to develop and evaluate an intervention program based on a theoretical premise involving social cognitive theory. This intervention involved 958 students from five Queensland secondary schools who participated in a 10-week program. The Cool Schools Peer Relationships Program was found to help reduce bullying behaviour through increased resiliency, relational skills building and improved mental health outcomes in those students who participated. Moreover, outcomes were greater for students with a lower initial capacity for resiliency against bullying. The implementation of a program such as the Cool Schools Peer Relationships program allows for increased awareness and support, a reduction in bully type behaviours and a greater sense of safety in the school community. Due to the context of this study there were limitations to the research. Traditionally, school settings present many challenges when conducting field research, and this was complicated by two influential events that occurred during the data collection period. The cross-sectional data were collected less than one-month after the terrorist attacks on the United States in 2001 and the secondary school that comprised the control group for the intervention study was subjected to several arson attacks.