Temperament, personality, and psychopathology in youth: A preregistered multilevel meta-analytic review and preregistered large-scale replication and extension.

The current pair of highly powered, preregistered studies estimates the associations between personality/temperament and youth psychopathology and evaluates the generalizability of these associations across diverse populations and research designs. In Study 1, a multilevel meta-analysis of 147 studies (k effects = 829, N = 46,369) quantified the cross-sectional associations among subjects aged 1.5-18, between five-factor model personality traits and internalizing/externalizing psychopathology dimensions within the Achenbach System of Empirically Based Assessments (Achenbach & Rescorla, 2001). All traits but openness evidenced bivariate associations with both psychopathology dimensions (r = |0.18-0.42|). After adjusting for the covariance between internalizing and externalizing, each dimension showed a distinct personality profile. Internalizing was associated with neuroticism (β = .42) and negative extraversion (β = -.37). Externalizing was associated with extraversion (β = .30), negative conscientiousness (β = -.46), and negative agreeableness (β = -.50). Most variance was driven by informant effects, particularly within the externalizing dimension and when personality and psychopathology were informed by the same person (i.e., mono-informant). Study 2 was a preregistered replication and extension of Study 1 in a large, demographically diverse cohort of 9- to 10-year-olds (N = 10,414; excluding diagnoses of schizophrenia, autism spectrum disorders, and substance use disorders) using cross-sectional, individual-participant, item-level data and measures of temperament corollary to Study 1 personality traits. Most of Study 1's personality associations with Achenbach System of Empirically Based Assessments internalizing and externalizing dimensions were replicated for higher order temperament scales (e.g., effortful control) and for their lower order scales (e.g., activation control). Again, mono-informant effects were more pronounced than cross-informant effects. Taken together, these studies provide the first quantitative synthesis of robust cross-sectional associations between personality and psychopathology in youth, highlighting the impact of mono-informant effects. Future longitudinal research may parse out directional relations as well. (PsycInfo Database Record (c) 2026 APA, all rights reserved).