Non-suicidal self-injury (NSSI) is a growing issue around the world and can be associated with a higher risk of suicide. One of the main functions of NSSI is to regulate emotions which is a hallmark struggle of individuals with Borderline Personality Disorder (BPD). There are very few treatment options for individuals who engage in NSSI unless they are at the extreme end of the spectrum or have BPD and there is a huge need for more early intervention options for those who do engage in NSSI. This study aimed to see if a 12-week explicit mentalization psychoeducation programme, which is originally part of a larger programme created to treat BPD, would be effective as an early intervention option for individuals who engage in NSSI. Participants (N=11) were recruited through their GPs. Measurements were taken at four timepoints over 9 months; baseline, pre-groups, post-groups, and follow-up. Measurements used were the Non-Suicidal Self-Injury Assessment Tool (NSSI-AT), Difficulties in Emotion Regulation Scale (DERS), The Mentalization Scale (MentS), Beck Anxiety Inventory (BAI), Beck Depression Inventory 2 (BDI-2), Inventory of Interpersonal Problems 32-item (IIP-32), and Severity Indices of Personality Problems (SIPP-118). Significant improvements were found for depressive symptoms, interpersonal problems, and self-control and relational capacities on the SIPP-118. Although no significant changes were found to NSSI in this study, the programme showed promise and with a larger sample size could produce significant results in the future.