The sample included 135 youths (113 males, age range 9–15 years, mean age 12±2.5 years, 85% Italian, 10% South-American and 5% from Asian and African countries), diagnosed and treated in our Hospital within the period 2005–2011. All the patients were diagnosed according to a clinical interview, the Kiddie Schedule for Affective Disorder and Schizophrenia for School-Age Present Life time Version (K-SADS-PL) (Kaufman et al., 1997), administered to patients and parents by trained child psychiatrists. Furthermore, the Child Behaviour Checklist (CBCL) (Achenbach and Edelbrock, 1983) was completed by parents. To determine IQ, all children were evaluated with the Wechsler Intelligence Scale for Children, 3rd Edition Revised (WISC-III-R) (Wechsler, 1991). Family socio-economic status was evaluated according to Hollingshead (2007). Inclusion criteria were: (1) DSM-IV diagnosis of Conduct Disorder (CD) or Oppositional Defiant Disorder (ODD) according to K-SADS-PL; (2) a Full Scale IQ above 85; and (3) a CBCL Externalizing Scale score above 63.