A developmental screening programme constructed for the use of Swedish child welfare centres on four-year-old children has been tested on a cohort of 471 children who have been followed up from the stage of early pregnancy. The results of the screening test were compared with data in the project using a multidisciplinary, longitudinal and prospective design. The test, which can be performed by a child welfare centre nurse and which is not time-consuming, includes four items summed up in a four-years-of-age score: the child is asked to name three easily recognizable objects, to draw a cross (according to a model), and to draw a man; in addition, an evaluation is made of speech development. On average, boys were found to have a lower score than girls. The results of the screening test were related to data available in the ongoing project; to the psychosocial conditions of the families, to foetal and perinatal factors (reduced optimality score according to Prechtl), to the presence of psychopathology, and to the results of Griffiths' developmental scales. The developmental screening score, which in most instances was associated with the Griffiths' scales, was found to be related to psychosocial problems in the family and to abnormal behaviour and psychiatric symptoms in the child, but not to reduced optimality scores. The results indicate that a relatively simple screening method is of value for the identification of children who are at risk of abnormal mental and behavioural development, and who may thus be in need of special care and attention.