Data are presented from two samples of preschool children to evaluate the reliability, concurrent validity, and predictive validity of the ADHD, ODD, and CD sections of the Diagnostic Interview Schedule for Children, Fourth Edition (DISC-IV). Information was obtained from a community sample of 128 children (M age = 53.16 months; 63 girls) and from a sample of 72 externalizing children (M age = 45.23 months; 31 girls) plus 25 control children (M age = 44.51 months; 8 girls). In both studies, the DISC-IV was administered to parents along with parent and teacher behavior rating scales, and teacher rating scales were obtained again later to evaluate the predictive validity of the DISC-IV (after approximately 6 months in Study 1, and 3 years in Study 2). The ADHD and ODD sections exhibited acceptable internal consistency in both studies, and showed concurrent validity with parent behavior rating scales. In both studies, the ADHD section was also concurrent with teacher reports. In Study 2, the ADHD, ODD, and CD sections distinguished externalizing children from controls. In both studies, the ADHD section predicted future teacher ratings beyond initial teacher ratings, and beyond initial parent rating scales; the ODD section similarly predicted later teacher ratings in Study 1. Findings provide strong support for the utility of the ADHD section for preschool children and moderate support for the ODD and CD sections.