Call for a transdiagnostic and ecologically valid assessment of youth psychopathology in daily life

Youth psychopathology is a pressing global challenge. High comorbidity rates and only moderate psychotherapy effects highlight the need for transdiagnostic approaches, which target mechanisms cutting across diagnostic categories to better understand the etiology and maintenance of mental disorders. Traditional diagnostic instruments, however, face limitations such as recall bias and inability to capture the dynamic, context-dependent nature of youth psychopathology. Recent advances in ecological momentary assessment (EMA) now enable real-time, naturalistic measurement, but EMA studies in youth rarely adopt a transdiagnostic focus, and transdiagnostic research has seldom incorporated EMA.This paper is a call for the integration of transdiagnostic science and EMA methods to advance clinical research and practice in youth. Although guidelines exist for EMA design in youth, recommendations on how to realize a transdiagnostic perspective using EMA is currently lacking. We summarize recent developments primarily in the field of adult research and outline key steps for the development and evaluation of a transdiagnostic EMA tool for youth. We conclude our call by outlining implications for transdiagnostic EMA research, including the potential of bridging theoretical transdiagnostic models and clinical applications.