The purpose of school vision screenings is to detect those children with vision problems that may impede normal development (eg, amblyopia, refractive error, strabismus, suppression). In a double-blind investigation, 483 schoolchildren, ranging in age from 5 to 13 years, had their vision screened using both the Random Dot E (RDE) stereogram and the Modified Clinical Technique (MCT). The validity of each technique was determined using the phi coefficient and was compared with results of similar reports in the literature for the Modified Clinical Technique, Snellen letter acuity, and vision-screening kits. Our data show that the RDE is more effective than five of six other techniques in identifying those children who need further visual examination. In addition, screening with the RDE can be taught to nonprofessionals in ten minutes or less, can be completed on each child within two minutes, and is inexpensive.