Assessing Core Beliefs in Adolescence: Psychometric Validation of the Negative Core Beliefs Inventory (NCBI)

Background: Core beliefs, per Beck’s cognitive theory, are fundamental views of self and others that shape emotion. Although the Negative Core Beliefs Inventory (NCBI) is validated in adults, evidence in adolescents—a key period for belief formation—remains limited. Objective: Validate the NCBI for adolescents by testing factorial structure, reliability, and validity. Methods: 146 students (12–17) in Salvador, Brazil, completed the NCBI plus anxiety, depression, and life satisfaction measures. Analyses included expert content review, EFA/CFA, graded response and generalized partial credit IRT models, and EBICglasso network modeling. Results: CFA supported the two-factor solution with acceptable fit (CFI = .89; RMSEA = .056). Internal consistency was good (most ω > .70); nCB-O ω = .87 and overall nCB-S ω = .93, but helplessness/vulnerability was lower (ω = .64). IRT indicated adequate discrimination for most items and greater information at higher trait levels; nCB-S9 performed poorly. Networks showed expected associations with anxiety, depression, and life satisfaction, supporting concurrent validity. Conclusions: The NCBI appears suitable for assessing negative core beliefs in adolescents and may aid early identification and intervention. Targeted refinement—particularly of nCB-S9 and the helplessness/vulnerability subscale—could strengthen psychometrics for this population. Broader samples and longitudinal designs are warranted to confirm stability and predictive validity.