The purpose of this study was to validate the Prescriptive Instructional Program for Educational Readiness (PIPER) for utilization as a criterion referenced test (CRT) among learning disabled children. The program consisted of behavioral objectives and diagnostic and/or mastery tasks and activities for each objective in the area of gross motor control, visual motor processes, auditory processes, language skills, and reasoning abilities. The participants included 181 children, aged six to eight, who were receiving supplementary instruction in a Title I Bridge to School Program. Findings included: (1) test-retest and interrater reliabilities are high; (2) use of performance tasks gives the teachers objective information for rating children; (3) the PIPER "tests" are generally sensitive to instruction; (4) comparison with the Metropolitan Readiness Test is unsatisfactory; and (5) further research to determine concurrent validity is required. A follow-up validation of the PIPER involved 78 of the children who had received Title I supplementary instruction the previous year and were known to the teacher rater. The data did not support use of the PIPER since its validity was highly questionable. (RL)