Achievement in reading and mathematics of students at elementary schools participating in the Columbus (Ohio) 1989 School Improvement Program (SIP) has improved for the seventh year in a row, but achievement of low income students remains below that of other students. The goal of SIP, an effective schools project, is to improve the academic achievement of students' basic skills and to lessen the disparity between students from different socioeconomic backgrounds. The Comprehensive Tests of Basic Skills (CTBS) at grades 2-8 and the Metropolitan Achievement Tests (MAT) at grade 1 were administered as a pretest and a posttest to 8,600 students in 33 schools. The following major findings are reported: (1) increases in reading comprehension achievement were slightly greater than expected; (2) increases in mathematics computation achievement were substantial, with 29.1 percent more of the students at grade level on the posttest than on the pretest; (3) low income students scored consistently lower than other students during the 7 years of the program; and (4) overall patterns of increases in student achievement have been consistent for the 7 years of the program. Statistical data are included on 13 tables. The following material is appended: (1) a list of schools participating in SIP, 1982-86; (2) a list of schools participating in schoolwide testing, 1988-89; and (3) a graph comparing various test scores to the normal curve. A list of four references is also appended. (FMW)