The Enright Arithmetic Program is a diagnostic-prescriptive program designed to facilitate an effective remedial effort. This paper evaluates the effect of the use of the program on the performance of students needing remedial education in mathematics. The program begins by establishing for each student the exact set of skills that the student currently needs to learn and also identifies the exact error pattern causing the student's current failure. Practice materials cross-referenced to the precise skill the student needs to learn are provided. In addition, the program indicates strategies designed to remediate the student's specific error pattern. The results measured by a city-wide mathematics test and a criterion-referenced test showed the positive effect of the program on the rate of skill acquisition of students in an intermediate school (grades 5 through 8). (YP)