Strengths Knowledge Scale (SKS) and Strengths Use Scale (SUS): Revisiting Psychometric Properties and Gender Invariance in the General Spanish Population.

The Strengths Knowledge Scale (SKS) and the Strengths Use Scale (SUS) are the most widely used instruments to measure strengths knowledge and strengths use, yet their psychometric properties have not been examined in the general Spanish population and the factor structure of the SUS remains inconclusive. This study examines the factor structure, reliability, construct validity, and gender invariance of both scales in 574 Spanish adults (M = 33.35, SD = 14.89). Exploratory Graph Analysis (EGA), Confirmatory Factor Analysis (CFA), Structural Equation Modeling (SEM), and measurement invariance analyses were conducted. A unidimensional structure was supported for both scales, although the SUS required correlated residuals between five item pairs to achieve adequate fit. Both scales showed good reliability. Strengths knowledge and strengths use were positively associated with emotional, psychological, and social well-being, while only strengths knowledge was additionally associated with lower anxious and depressive symptomatology. Both scales demonstrated scalar gender invariance. These findings support the psychometric adequacy of the use of the SKS and SUS in the Spanish general population.