Background: Deliberate self-harm (DSH) is reported by between 5 and 17% of youth aged 14-25 years. Current management measures focus on repetition prevention in high-risk groups. Objectives: To examine risk factors and predictors of DSH and DSH repetition in a community sample, by gender. Methods: A prospective cohort of 20 822 young adults (aged 17-24 years) was recruited when obtaining their driving license. A random sample of 5000 was approached for follow-up 12-18 months; 2991 (60%) responded and formed the cohort for this analysis. Patterns of self-harm, using a modified Beck Suicide Inventory, were investigated with logistic regression. Results: DSH was reported by 4.1% (123/2991) at baseline. Over the following 12 months, 3.0% (90/2991) reported new instances of DSH which included 20% (25) respondents who had engaged in DSH at baseline. Psychological distress was a risk factor for engaging in DSH in the past 12 months, OR 3.55 (95% CI 2.06-6.14). Although several clinical risk factors differed between genders, high alcohol use, OR 23.6 (95% CI 3.64-153) and psychological distress, OR 4.97 (95% CI 1.08-22.9) were significant risk factors for repeat DSH in both males and females. Conclusion: In this community cohort, 1 in 25 youth had self-harmed in the year prior; of these, 4 in 5 did not repeat DSH over the following year. High alcohol use stands out as a strong risk factor for DSH repetition. Assessing alcohol use may help clinicians identify those who are at greatest risk for repetitive self-harm.