Background Injury is a leading cause of adolescent death. Risk-taking behaviours, including unsafe road behaviours, violence and alcohol use, are primary contributors. Recent research suggests adolescents look out for their friends and engage in protective behaviour to reduce others' involvement in risk-taking. A positive school environment, and particularly students' school connectedness, is also associated with reduced injury-risks.

Aim This study aimed to understand the role of school connectedness in adolescents' intentions to protect and prevent their friends from involvement in alcohol use, fights, drink driving and unlicensed driving.

Method Surveys were completed by 540 13–14-year-old students (49% male). Four sequential logistic regression analyses were conducted to determine whether school connectedness statistically predicted intentions to protect friends from injury-risk behaviours. Gender and ethnicity were entered at step 1, students' own risk behaviour at step 2, and school connectedness scores at step 3 for all analyses.

Results School connectedness significantly predicted intentions to protect friends from all four injury-risk behaviours, after accounting for the variance attributable to sex, ethnicity and adolescents' own involvement in injury-risks.

Significance School connectedness is negatively associated with adolescents' own injury-risk behaviours. This research extends our knowledge of this critical protective factor, as it shows that students who are connected to school are also more likely to protect their friends from alcohol use, violence and unsafe road behaviours. School connectedness may therefore be an important factor to target in school-based prevention programmes, both to reduce adolescents' own injury-risk behaviour and to increase injury prevention among friends.