The testing of every fourth-grade classroom in Massachusetts was carried out in an effort to answer the following questions: (1) What are the levels of mastery of basic skills in Massachusetts fourth grades? Are there differences in achievement between skills?; (2) What educational needs can be inferred for Massachusetts' students, based on basic skills testing?; (3) Do testing data reveal the influence of Federal programs?; (4) Does the product of education vary according to available resources--financial outlay, professional support, materials?; and (5) Are there regional variations in abilities and achievement? Aptitude and achievement data were obtained for 324 school systems, 1488 schools, and 85,382 fourth-grade children. The test instruments used were the Comprehensive Tests of Basic Skills and the Short Form Test of Academic Aptitude published by CTB/McGraw-Hill. Three different reports of the test data were supplied to all school systems. The test data showed that the state as a whole exceeded the national norms; the mean "obtained" scores were significantly higher than the "anticipated" scores in all areas measured by the tests of basic skills. Highest scores were in reading comprehension and the lowest in arithmetic. From the test results, it was concluded that Massachusetts fourth graders are slightly higher than the national norms in all areas measured. Correlations between the subtest total mean scores by school are statistically significant and very high. Schools that did well on one subtest generally did well on all subtests. A survey of school superintendents showed that 98% used the test data. (DB)