The purpose of this study was to test the factor structure of the Inventory of Callous-Unemotional Traits (ICU; Frick, 2004 ) and to study the relation between the derived dimensions and external variables in a community sample of preschool children. A total of 622 children 3 and 4 years of age were assessed with a semistructured diagnostic interview, the ICU, and other questionnaires on psychopathology, temperament, and executive functioning, completed by parents and teachers. Confirmatory factor analysis derived from teachers' ICU responses yielded three dimensions: Callousness, Uncaring, and Unemotional. Callousness and Uncaring subscale scores correlated with the specific scales related to aggressive behavior, temperament, executive functioning, and conduct problems. The ICU scale scores discriminated cross-sectionally oppositional defiant disorder (ODD) and conduct disorder (CD) diagnoses, aggressive and nonaggressive symptoms of CD, use of services, and ODD/CD-related family burden. Longitudinally, Callousness subscale score at age 3 predicted ODD or CD diagnosis at age 4. Unemotional was not associated with aggressive measures, but it was linked to anxiety disorders cross-sectionally and longitudinally. Callous-Unemotional traits contributed significantly to predicting disruptive behavior disorders controlling for sex, temperament, and executive functioning (predictive accuracy between 3 and 5%). The ICU is a promising questionnaire for identifying early Callous and Uncaring traits in preschool years that may help in the identification of a subset of preschool children who might have severe behavioral problems.