Non-suicidal self-injury (NSSI) is a significant mental health issue among children and adolescents, characterized by deliberate, self-inflicted harm to body tissue without suicidal intent. NSSI is a robust predictor of later suicide attempts and is commonly linked to various psychiatric comorbidities. Ongoing debate concerns whether NSSI and suicidal behavior should be classified as separate entities or as points along a continuum of self-harm. The continuum perspective underscores the necessity of identifying risk factors that contribute to progression from NSSI to suicidal behavior. This paper reviews current literature on Non-Suicidal Self-Injury (NSSI) and introduces a research project aimed at identifying predictors of transition from NSSI to Suicidal Self-Injurious Behaviour (SSIB) in clinical adolescent populations. The primary objective is to inform the development of early preventive interventions. The study will use a longitudinal design, enrolling adolescents aged 13 to 17 years from primary care and child psychiatry clinics. Eligibility requires meeting the proposed Diagnostic and Statistical Manual of Mental Disorders, Fifth Edition (DSM-5) criteria for Non-Suicidal Self-Injury (NSSI). The protocol includes structured interviews such as the Self-Injurious Thoughts and Behaviors Interview (SITBI) and the Suicide Attempt Self-Injury Interview (SASII), as well as selfreport instruments including the Suicidal Behaviors Questionnaire-Revised (SBQ-R), Childrenʹs Depression Inventory 2 (CDI-2), Difficulties in Emotion Regulation Scale (DERS), and Youth Self- Report (YSR). These tools will assess self-injury, suicidality, emotional symptoms, emotion regulation, and overall functioning. Assessments will occur at baseline and at 1, 3, and 6 months to monitor changes in risk and resilience. Recognizing Non-Suicidal Self-Injury (NSSI) as part of a continuum of psychopathological development is essential for clinical practice. The anticipated findings from this research may validate NSSI diagnostic criteria, identify critical risk markers for escalation to suicidal behavior, and support the creation of more effective, individualized screening, prevention, and treatment strategies. These advances aim to reduce morbidity and mortality among vulnerable adolescents.