Objective: To explore the contributions of genetic and environmental influences to individual variation and covariation of the Child Behavior Checklist (CBCL) DSM-oriented scales (DOS) originally proposed by Achenbach and associates in 2001. Method: A classic twin study of 398 twin pairs ages 8 to 17 years belonging to the population-based Italian Twin Registry, assessed by parents using the CBCL for Ages 6 to 18 (CBCL/6-18). Results: Univariate analyses showed that compared with the classic CBCL/6-18 empirical subscales, the DOS have higher heritability (lowest 0.54 for Anxiety Problems, highest 0.71 for Conduct Problems) and simpler causal structure in that the phenotypic variance was satisfactorily explained by additive genetic and unique environmental factors only. Multivariate analyses showed that the causes of phenotypic correlation among the different DOS can be attributed to one common genetic factor and to two idiosyncratic environmental factors, each loading differently on the Internalizing (Anxiety and Affective Problems) and the Externalizing(Attention-Deficit/Hyperactivity, Oppositional Defiant, and Conduct Problems) CBCL/6-18 DOS. Conclusions: Several common risk factors of both genetic and environmental nature can simultaneously affect a child's proneness to develop the psychopathological signs and symptoms captured by the CBCL/6-18 DOS. (Contains 4 tables and 1 figure.)