This paper documents the prevalence of Adverse Childhood Experiences in a sample of 130 young people aged under 18 who present high levels of risk in relation to serious violent, sexual or extremist behaviours. The paper also considers the impact of childhood bereavement which, although known to be a common feature in the lives of young people involved in offending, is rarely documented in Adverse Childhood Experience studies. The paper also presents potential evidence of gender effects and begins to reflect on how gender might interact with how young people, and the systems and professionals around them, respond to adversity in childhood.