biostudies-literatureUnknown32(6)Zheng HPrevious 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 (<i>n</i> = 99, 2,132 daily reports) and young adults (<i>n</i> = 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 (<i>p</i> 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.Assessment899-920https://www.ebi.ac.uk/biostudies/studies/S-EPMC12290237biostudies-literatureUnderstanding the Within- and Between-Person Structure of Daily Psychopathology Among Adolescents and Young Adults.PMC12290237Zheng YZheng HfalseUnderstanding the Within- and Between-Person Structure of Daily Psychopathology Among Adolescents and Young Adults.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 (<i>n</i> = 99, 2,132 daily reports) and young adults (<i>n</i> = 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 (<i>p</i> 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.2025-01-01T00:00:00Z2025 Sep2026-03-15T18:40:21.601Z2025-08-13T03:04:31.055ZS-EPMC122902373934495710.1177/10731911241283908