Trauma-informed approaches emerged partly in response to research demonstrating that trauma is widespread across society, that it is highly correlated with mental health and that this is a costly public health issue. The fundamental shift in providing support using a trauma-informed approach is to move from thinking ‘What is wrong with you?’ to considering ‘What happened to you?’. This article, authored by trauma survivors and service providers, describes trauma-informed approaches to mental healthcare, why they are needed and how barriers can be overcome so that they can be implemented as an organisational change process. It also describes how past trauma can be understood as the cause of mental distress for many service users, how service users can be retraumatised by ‘trauma-uninformed’ staff and how staff can experience vicariously the service user's trauma and can themselves be traumatised by practices such as restraint and seclusion. Trauma-informed mental healthcare offers opportunities to improve service users' experiences, improve working environments for staff, increase job satisfaction and reduce stress levels by improving the relationships between staff and patients through greater understanding, respect and trust.