Diagnosis in psychiatry continues to struggle to fulfil its key purposes, namely to guide treatment and to predict outcome. A clinical staging model, widely used in clinical medicine, could improve the utility of diagnosis in psychiatry, especially in young people with emerging disorders. Clinical staging has immediate potential to improve the logic and timing of interventions in psychiatry, as it does in many complex and potentially serious medical disorders. Interventions could be evaluated in terms of their ability to prevent or delay progression from earlier to later stages of a disorder, and selected by consumers and clinicians on the basis of clear-cut risk-benefit criteria. This would ensure that, as treatments are offered earlier, they remain safe, acceptable and affordable, and potentially more effective. Biological variables and a range of candidate risk and protective factors could be studied within and across stages, and their role, specificity and centrality in risk, onset and progression of disorders clarified. In this way, a clinicopathological framework could be progressively constructed. Clinical staging, with restructuring across and within diagnostic boundaries and explicit operational criteria for extent and progression of disorder, should be actively explored in psychiatry as a heuristic strategy for developing and evaluating earlier, safer, and more effective clinical interventions, and for clarifying the biological basis of psychiatric disorders. Young people with emerging mental and substance use disorders could be the main beneficiaries.