Key Data Systems has developed several ways to help district and school administrators manage and maintain their CELDT data. In the fall of 2001, school districts across the state of California began administering the California English Language Development Test (CELDT) to all English Learner (EL) students. Since that time, Key Data Systems has developed several services to help district administrators manage and maintain their CELDT data, including AMAO Estimates, Movement analysis of CELDT Proficiency levels from year to year, and multiple assessment correlations using California Standards Test (CST), and local assessment data.