The Denver Prescreening Developmental Questionnaire (PDQ), a parent-answered questionnaire, has been revised to extend the age of children who can be screened to those from 6 years down to birth, to make the test items more challenging for children and more informative for parents, and to make it easier for professionals to compare a child's performance with Denver Developmental Screening Test (DDST) norms. This Revised PDQ (R-PDQ) identified 84% of nonnormal DDST results. Test-retest reliability over 1 week was 94.1%, and parent-teacher agreement was 83%. A field test of the R-PDQ, conducted in a variety of settings with 1434 children, revealed that suspect scores on first-stage screening varied with the setting, from 15.6% in private pediatric practices to 50.5% in Head Start and urban day care centers. Parents found the R-PDQ interesting and easy to complete; health professionals found it economical and easy to interpret. We recommend that the R-PDQ be coupled with a brief developmental examination, and that the R-PDQ be used in busy office settings and community mass screening programs.