The authors argue that traditional diagnostic systems are poorly suited to capturing the complex, evolving, and often overlapping nature of mental health difficulties in young people. They propose a transdiagnostic clinical staging framework that conceptualises mental illness as progressing along a continuum, from early risk states and non-specific symptoms to more severe, persistent, and recurrent disorders. The framework aims to improve early intervention, treatment selection, and understanding of illness trajectories by focusing on both progression and extension of psychopathology. Overall, the paper provides a foundational model for organising youth mental health care around developmental pathways rather than fixed diagnostic categories.