The history of a statewide effort to improve student learning in Missouri by adopting the concept of an Instructional Management System (IMS) with desired learned outcomes determining both instruction and testing was suggested to local school districts in 1980. In 1985, legislation provided funds and authority to engage large groups of teachers in creating criterion-referenced tests in reading and language arts, mathematics, science, and social studies and civics for various age groups. More than 800 educators were involved in developing Missouri's key skills. Over 200 teachers and administrators were involved in item writing, while another group of over 200 reviewed items for agreement with the key skills and for quality. With the help of consultants and further teacher review, field test forms were prepared and administered in April 1986. The original four forms were replaced by three revisions for an additional field trial conducted in 1987. The final version of the Missouri Mastery and Achievement Test (MMAT) batteries consists of 34 criterion-referenced tests assessing student performance in grades 2 through 10. Results of the 1988 administration of the MMAT document large achievement gains for Missouri students. Thirteen tables present data from test development. (SLD)