Background: Deliberate self-harm (DSH) in young people is an important public health issue. To prevent DSH, more knowledge is needed about its prevalence and associated contextual factors in community samples of adolescents. Aims: To determine the prevalence of deliberate self-harm in 17-year-old Swedish students and to explore the association of demographic variables, psychological distress, experiences of violence, and school-related factors with DSH. Methods: Data were derived from a cross-sectional study in which 17-year-old students completed questionnaires during school hours (n=1,663; 78.3%). The variables used in this analysis are as follows: deliberate self-harm, demographic variables, psychological distress, experiences of violence, and school-related factors. Data were analysed using chi-squared statistics and logistic regression. Results: The lifetime prevalence of DSH was 17%, and it was more common among girls (23.3%) than boys (10.5%). There were considerable socioeconomic differences in reports of DSH. Psychological distress was strongly associated with DSH in both boys and girls, as were experiences of bullying, sexual harassment, physical violence and sexual assault. Social support, safety and academic factors in school were related to reports of DSH in both girls and boys. There were some gender differences with respect to which factors were associated with DSH. Conclusions: Deliberate self-harm is common and more frequently reported by girls than boys. Psychological distress, experiences of different types of violence, and school-related factors (academic, social and safety-related), should be considered risk factors for DSH in young people. Findings can be applied to health-promotion policy and interventions in various contexts, for example schools.