The intent of the No Child Left Behind (NCLB) Act of 2001 is to hold schools accountable for ensuring that all their students achieve mastery in reading and math, with a particular focus on groups that have traditionally been left behind. Under NCLB, states submit accountability plans to the U.S. Department of Education detailing the rules and policies to be used in tracking the adequate yearly progress (AYP) of schools toward these goals. This report examines Florida's NCLB accountability system, particularly how its various rules, criteria and practices result in schools either making AYP, or not making AYP. It also gauges how tough Florida's system is compared with other states. Only four schools in the study make AYP in Florida: (1) Florida's cut scores range from the 30th to the 53rd percentile, making proficiency standards are relatively hard to achieve; and (2) Florida does not apply a confidence interval to proficiency rate calculations,; therefore, schools have greater difficulty achieving their annual targets than they would in states that employ confidence intervals. Conversely, some schools in the study make AYP in Florida but do not in most other states, likely because the minimum subgroup size in Florida tends to be large, meaning Florida schools will be accountable to fewer groups than schools in many other states. Compared to the other 27 states examined, Florida places in the middle of the distribution in terms of the number of schools making AYP. The report concludes that although in some respects, Florida's NCLB accountability system is working as intended by the legislation, NCLB shortcomings are also evident, and should be considerations for Congress in future reauthorizations of the act. (Contains 9 footnotes, 4 figures, and 6 tables.) [For "The Accountability Illusion," see ED504712. For individual state reports, see ED504680-ED504694, ED504700-ED504711 and ED504719.]