Self-harm and suicidal behaviours in children and young people are increasingly common. These behaviours sit on a broad continuum from relatively risk-free behaviours that may be used as coping mechanisms to life-threatening acts with suicidal intent. Self-harm is more likely in patients with co-morbid mental health conditions, but most young people who self-harm do not have a mental health diagnosis. Family adversity, educational stressors, physical health illnesses, bullying, and substance misuse may all increase the risk of self-harm. Young people may find internet support groups helpful as they may value the discretion of online support for a behaviour about which they may be embarrassed. However some internet sites teach young people more dangerous self-harming strategies and young people may be bullied or encouraged to complete suicide. Historical methods of risk stratification have poor predictive validity and it is instead recommended that clinicians engage collaboratively with young people in an individualised approach to risk assessment, developing a detailed risk formulation and safety plan. Young people who self-harm are 30 times more likely to die by suicide, and it appears that those from minority groups are at greater risk. Mild self-harm may only require a ‘listening ear’ from a trusted friend or adult, but more severe difficulties may need professional assistance from mental health services that should be trauma-informed and relational in approach, offering evidence-based interventions such as DBT-A or MBT-A. Crisis services should be responsive and flexible to young people’s needs so as to be able to engage them and de-escalate risks effectively.