Assessment, Ahead of Print.
Previous investigations on the underlying structure of psychopathology symptoms primarily focused at the between-person level and among adult samples. This study used two independent Canadian samples with month-long daily diary designs to investigate daily psychopathology structure at both within- and between-person level among adolescents (n = 99, 2,132 daily reports) and young adults (n = 313, 6,431 and 4,018 daily reports at each wave). Four mainstream types of psychopathology structure were compared based on a comprehensive set of standards. The results suggest that the general factor of psychopathology (p factor) derived from the higher-order and bifactor models performed similarly well at both within- and between-person levels, while the specific factors estimated in the bifactor models demonstrated low reliability and consistency over time. Psychopathology manifests as multidimensional at the within-person level but unidimensional at the between-person level. The current findings inform the development of future prevention and intervention programs by supporting the adoption of transdiagnostic treatment that addresses multiple psychopathology symptoms with a holistic approach.