April 1990 marked the tenth year of the effort mandated by the Arizona State Legislature to assess student performance through nationally standardized norm-referenced achievement testing in reading, grammar, and mathematics for students in grades 1 through 12. This was the sixth year the Iowa Tests of Basic Skills were administered to students in grades 1 through 8 and the second year the Tests of Achievement and Proficiency were administered to students in grades 9 through 12. Student performance across all grades and statewide performance within grade are summarized for 469,601 students enrolled in 985 schools in 214 districts. Gender, racial, and ethnic differences are also identified. Only representative samples of students were tested in grades 1 and 12. Arizona students collectively scored in the average ranges in reading, language, and mathematics across all grades based on 1987-88 national norms. In 33 comparisons with state data from the previous year, 19 areas showed growth, two remained the same, and 12 declined. Twenty-six bar graphs and 37 tables contain the test results. The appendixes provide the 1990 percentile ranks for students in grades 1-12 in reading, language, and mathematics. (SLD)