Described are the rationale, development and utility with mentally retarded children of the Peabody Mathematics Readiness Test (PMRT), an instrument designed to assess mathematical readiness of normal first graders and identify children who would experience difficulty with first grade mathematics. It is explained that the PMRT was intended to pinpoint areas of deficiency and help devise appropriate remediation activities. The PMRT is said to be composed of two parts: discrimination items and line drawings to be copied. Further, it is noted that the test can be group administered, has a theoretical rationale, and has been empirically validated. Discussion of the PMRT's historical development covers such aspects as establishment of scoring schemes and weighting systems, as well as research on the effectiveness of remedial materials developed for normal first grade students. Reviewed is an experiment in which 737 normal first grade students and 175 educable mentally retarded students matched for MA were administered the PMRT. Cited among findings is the basically equal performance between normal first grade and mentally retarded Ss on the discrimination tasks of the PMRT. (CL)