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 Delaware'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 Delaware's system is compared with other states. Delaware's mix of rules means that several schools make AYP in Delaware that do not in most of the other 27 states. Although Delaware's proficiency standards are relatively easy compared to other states, its annual targets in reading are relatively difficult to achieve: 68 percent of a given population in any school would have to be proficient on the state reading exam for the school to make AYP in 2008. Every school with a limited English proficient (LEP) subgroup failed to make AYP in Delaware. Compared to the other 27 states examined, Delaware places in the middle of the distribution in terms of the number of schools making AYP. The report concludes that although in some respects, Delaware'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 11 footnotes, 5 figures, and 6 tables.) [For "The Accountability Illusion," see ED504712. For individual state reports, see ED504680-ED504694, ED504700-ED504711 and ED504719.]