Appropriate indication for prevention needs a screening for early signs of-in this case-externalising behavior (inattentiveness, hyperactivity, impulsivity, and aggression). For this reason, 13 items of the Child Behavior Checklist (CBCL/4-18) were selected by empirical (item total correlation in a representative sample, factor analyses) and clinical (expert rating) decision, and included in a short questionnaire for parents and kindergarten teachers (P/T) of children aged 3 to 6 years, focussing on the cross-informant view of externalising behavior. Findings of exploratory factor analysis based on a small sample (NT = 597/Np = 424) generated in the city of Cologne could be replicated by confirmatory analyses including a more extensive sample from Cologne (NT = 2248/Np = 1702) and another sample from the city of Brunswick (NT = 599/Np = 521) and confirmed a 7-item-scale of externalising behavior. 20% of the children within the sample indicated by the 85th percentile of the cross-informant externalising scale could be classified as showing disruptive behavior following DSM-IV criteria.