The mortality and morbidity resulting from serious trauma in adolescence, particularly head and spinal cord injury, constitutes a health problem of major proportions Although many community-based prevention programmes have been reported in this last decade, few of these describe an evaluation component In this study, a school-based prevention programme was developed by a peer group and presented by them to high-risk adolescents The study aimed to test the efficacy of this intervention compared to the delivery of a prevention presentation to a similar group by a health care professional and compared to a control group Measures of health locus of control, self-efficacy and behavioural intent were supplemented by open-ended items related to risk-taking behaviour change At post-test and at 4-month follow-up, there was little evidence in the quantitative measures to support the effectiveness of the intervention for reducing injury risk factors More encouraging findings were seen in the qualitative data Explanations for why the intervention did not result in the expected outcomes are offered