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 Michigan'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 Michigan's system is compared with other states. Michigan's proficiency standards are relatively easy compared to other states in the study: none are above the 35th percentile according to NWEA norms. Unlike most states, which apply a confidence interval to measurements of group proficiency rates, Michigan applies a standard error to individual student scores, increasing the number of students whose scores are considered passing. A final contributing factor to the large number of schools making AYP in Michigan is that the state applies different annual targets for different grades and subjects. Compared to the other 27 states examined, Michigan places at the high end of the distribution in terms of the number of schools making AYP. The report concludes that although in some respects, Michigan'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.]