The predictive validity of the Simultaneous Technique for Acuity and Readiness Testing (START), a developmental screening approach, was assessed with school performance as outcome criterion. The sample consisted of over 1,000 rural, preschool children between 54 and 66 months of age who were screened over 3 successive years. Follow-up achievement data were obtained at kindergarten, first, and second grade for Cohort 1, and at first grade only for Cohorts 2 and 3. Special education and retention information were obtained for all children. Participants were classified as having either "poor" or "satisfactory" school outcomes based on both achievement and tracking data. Summary START scores were used to classify the children into low, borderline, and pass categories, which were subsequently cross-classified with the school outcome categories. Findings indicated that among the 75 children in Cohort 1 who scored low on the START, 36 percent had poor school outcomes by kindergarten, 53 percent by first grade, and 59 percent by second grade. Predictive value was substantially lower for Cohorts 2 and 3. Specificity and sensitivity indices were similar across cohorts. Results with stratified samples who were administered standard diagnostic tests suggested that START should serve well as a screening test in pediatric practice. (RH)