Behavioral/emotional problems and competencies in 2,148 international adoptees aged 10 to 15 years were compared with those in a same-aged sample of 933 children from the general population using the Achenbach Child Behavior Checklist. Parents reported more externalizing problem behavior for adopted than nonadopted children. More than twice as many 12- to 15-year-old adopted boys were scored above the cutoff criterion for problem behavior than nonadopted boys of the same age. For adopted boys in this age range especially high scores were obtained on the Delinquent and Hyperactive syndromes. Adopted children were scored less competent than nonadopted children in their social and academic functioning, whereas adopted children were found to be more active in nonsports activities and to function somewhat better than nonadopted children in sports and nonsports activities. In contrast to the effect of parental occupational level on competent scores for normative American and Dutch samples, adopted children from lower SES showed better academic performance, were less often referred to special classes, and had less other school problems than adopted children from higher SES.