The scope of the present study was first to evaluate the cross-cultural reliability and validity of the Social Emotional Questionnaire (SEQ) and second to estimate and compare the prevalence rates of childhood developmental and psychiatric disorders in the general population of young children in the Netherlands and Greece. To this end, the caregivers of 1748 Dutch and 384 Greek 4-12-year-old children from the general population completed the SEQ. The number of children displaying symptoms of childhood developmental disorders was estimated by applying the Diagnostic and Statistical Manual of Mental Disorders-IV criteria of symptom occurrence. Results showed that the reliability and the construct validity of the SEQ were acceptable in both countries and for all the age-groups of children. Concerning the prevalence, the Greek children were found to display overall significantly more symptoms of developmental disorders than the Dutch children. However, when the number of children suffering from psychiatric symptoms in the clinical range was estimated using the clinical criteria provided by categorical classification systems, no statistical significant differences emerged between the two countries. This finding suggests that when the criterion of clinical impairment is applied in diagnostic procedures, the number of children suffering from severe psychiatric disorders is about equal in the two countries. The implications of the study are discussed. (Contains 5 tables and 2 figures.)