A longitudinal study was conducted to assess (1) the validity of the Denver Prescreening Developmental Questionnaire (DPDQ) in a predominantly black, lower socioeconomic population, and (2) the effect of an educational package in increasing parental accuracy in responses to the DPDQ. Randomly selected mothers of 127 infants enrolled in a follow-up program were provided written and audiovisual material describing developmental behaviors; each mother recorded her child's subsequent development at 2- and 3-, 6- and 9-month visits. Seventy-eight of the infants were followed for 3 months, while 53 and 33 infants were followed for 6 and 9 months, respectively. Mean agreement scores between parental responses to the DPDQ and development observed via the Denver Developmental Screening Test exceeded 90 per cent at 3, 6, and 9 months, respectively. Item agreement scores of the experimental and control groups were equivalent, thereby demonstrating the educational program failed to increase parents' accuracy of response. Neither age nor educational level of mothers influenced the accuracy of responses to the DPDQ. The rate of overreferrals to pediatricians was low (12.8 per cent). These results attest to the usefulness of the DPDQ in lower socioeconomic black populations, but raise questions about parent education through audiovisual and written materials. (Author/DB)