Colorado conducts an assessment program to provide a statewide profile of student achievement. Results for fall 1988 and fall 1991 are presented in a series of tables. A standardized, nationally norm-referenced achievement test, the Iowa Tests of Basic Skills, was administered in 1988 to students in grades 4, 7, and 10, and again to the same grades in 1991. The same general sampling procedures were used in both years to assure that both were valid and representative samples. To provide a profile of the average Colorado student at each of the three grades, the results in this report represent national percentile ranks for students of the mean developmental scale score in each learning area on the basic test battery. To better profile changes in achievement over time, mean developmental scale scores are also presented. Percentages of student ranking in the upper decile, the upper quartile, the lower quartile, and the bottom decile are also presented. For each of these areas, results are presented by sex, race and ethnicity, district size, and geographic finance category. Included are 47 tables and a list of the school districts in Colorado by size. (SLD)