The purpose of this study was to test the applicability of a standardised procedure for assessing Icelandic children's behaviour/emotional problems and competencies, and to identify differences related to demographic variables. This study focuses upon the method of using the Child Behavior Checklist (CBCL) by Achenbach to estimate the reported prevalence of parents and adolescents of emotional and behaviour problems in children from 2-16 years of age and self-reported prevalence of adolescents from 11-18 years, selected at random from the general population, both in urban and rural areas. The information was obtained by mailing checklists with a letter to parents of children 2-10 years of age. The checklists for adolescents 11-18 years of age were distributed by teachers in school. Those adolescents who were not in school received the checklists by mail at their homes. The Child Behavior Checklists used for analyses were completed by 109 parents of 2-3 year old children; 943 parents of 4-16 year old children, and 545 non-referred adolescents from the general population. The rate of response was lowest for the youngest age group 47%, but increased to 62% with increasing age of the child. The response rate among the adolescents answering the Youth Self Report was 64%. Comparisons with the Child Behavior Checklists from this study are presented with Dutch, American, French, Canadian, German and Chilean samples and show striking similarities in four of these countries on the behaviour/emotional problems reported.