This study aimed to investigate the impact of disclosure of non-suicidal self-injury (NSSI) by young people and to investigate these effects over time. Overall, the study results indicate that disclosure of NSSI is a positive behaviour that should be encouraged in young people. Disclosure of NSSI was found to facilitate further help-seeking from peers, improve coping and reduce suicidality. However, disclosure to peers may reduce perceived social support and encourage NSSI in others. Conversely, confiding in an adult may be an important protective factor, increasing both adaptive coping skills and the belief in the ability to employ alternative coping skills, and possibly reducing the severity of NSSI. Importantly, over 40 % of young people had not disclosed their NSSI to anyone. This highlights the secretive nature of NSSI and the need to encourage disclosure. The findings provide potential avenues for combatting help-negation related to NSSI, suggesting information and support initiatives should be primarily directed to the young person’s peer group and to parents. Parents and friends of young people who self-injure should also be encouraged to model the use of problem-focused coping strategies.