The purpose of this technical assistance paper is to provide a description of the procedures used to determine school improvement ratings for alternative schools and ESE centers for the most recently completed school year. School improvement ratings are part of Florida's school accountability system, which originated with the Florida Legislature's passage of Assistance Plus (A+) legislation in 1999. Florida is one of the few states that can track student demographic information from year to year and is the first to track annual student learning gains based on the state's academic standards. School improvement ratings are calculated as defined in Florida Administrative Code Rule 6A-1.099822, under the authority of sections 1008.341 and 1008.345, Florida Statutes. Based on statutory criteria, alternative schools and ESE centers are identified by the Florida Department of Education with input from Florida's school districts. Once these schools are identified for the reporting year, the administration of each school is provided the opportunity to choose, for an annual accountability evaluation, either a regular school grade (using criteria applicable to traditional schools receiving school grades) or a school improvement rating (using criteria described in Rule 6A-1.099822) for the applicable reporting year. If the administration of an alternative school does not choose either option, the school will by default be assigned a school improvement rating. Schools that elect a school improvement rating in lieu of a school grade will have the rating based on a comparison of current-year and prior-year learning gains for eligible students in reading and mathematics. This paper contains two sections: I. Overview, and II. Process for Calculating School Improvement Ratings. These sections describe procedures for determining a school's final rating and are intended for audiences who are interested in the details of determining school improvement ratings for alternative schools and ESE centers. [This document was prepared by the Bureau of Accountability Reporting; Division of Accountability, Research, and Measurement.]