Self-harm is when someone intentionally hurts or damages their body. In some instances, self-harm is accompanied by suicidal thoughts and an intent to die, and in other cases not. For some young people, intent can fluctuate and change over time. Self-harm is a behaviour that can occur in a whole range of disorders, including depression, Borderline Personality Disorder (BPD), psychosis, eating disorders, anxiety, and/or substance use. Some people self-harm once, whereas for others it can be a repeated behaviour. This factsheet explores reasons for self-harm in young people to help us understand and respond appropriately, drawing on the latest evidence from research.