The Comprehensive School Mathematics Program (CSMP) is a program of CEMREL, Inc., one of the national educational laboratories, and was funded by the National Institute of Education (NIE). Its major purpose is the development of curriculum materials for grades kindergarten through 6. Two schools began using CSMP in fall 1978, with the curriculum begun with all students through fourth grade, rather than the more common grade-by-grade approach that begins with only first-grade classes. A series of tests administered in 1978, 1979, and 1980 were designed to compare the performance of students before the introduction of CSMP, after one year's experience and after two years' experience. Results indicated: 1) On MANS tests, significant improvement was found from 1978 to 1980, which was consistent with previous CSMP and non-CSMP comparisons made with the same tests; 2) The kinds of tests which the 1980 group did relatively better on were also ones on which CSMP superiority had been demonstrated in previous studies; and 3) On second-grade standardized tests, virtually no change at either school in mathematics scores related to reading scores. However, there was usually a small decrease in the first year of CSMP for third- and fourth-grade pupils, followed by a "more-than-compensating" gain the second year. (MP)