Research Findings: Few rating scales measure social competence in very young Spanish or Catalan children. We aimed to analyze the psychometric characteristics of the California Preschool Social Competence Scale (CPSCS) when applied to a Spanish- and Catalan-speaking population. Children were rated by their respective teachers within 6 months following their 4th birthday in two population-based birth cohorts in Spain (N = 378). A confirmatory factor analysis (CFA) was used to compare the underlying structure of the Spanish-Catalan version with that of the original version. Cronbach's alpha coefficient was used to determine the internal consistency of each of the confirmed factors. Cohen's kappa formula was used to calculate the test-retest reliability in a small subset of children who were rated again one month later. Five correlated factors (Considerateness, Task Orientation, Extraversion, Verbal Facility, and Response to Unfamiliar) were optimally confirmed as a result of CFA. The first three factors had robust internal consistency. The kappa coefficient was satisfactory in 29 items out of 30. Children's cognitive abilities as assessed by the McCarthy Scales, children's gender, maternal social class and level of education were related to the social competence scores as indicators of criterion-related factors. Practice or Policy: The bilingual version of the CPSCS has good psychometric properties allowing it to be used in further studies in either Spanish or Catalan populations. (Contains 5 tables.)