With the congressional effort to reauthorize the No Child Left Behind Act at a standstill, schools and districts will need to stay on target toward the law's goal of 100 percent proficiency in reading and mathematics in the next six years--or else face sanctions or interventions. That process will be especially hard in 23 states that made the achievement targets relatively easy to meet in the first years of implementing the 6-year-old federal law. Starting with the current school year, schools and districts in those states will have to make annual gains of 10 percentage points or more in the proportion of students scoring as proficient in those subjects, says a report released in May. The process of determining whether a school makes adequate yearly progress, or AYP, under the federal law is so complicated that it's impossible to estimate how many schools will fail to meet their AYP targets because their state will require these more-extensive achievement gains, said Jack Jennings, the president of the Center on Education Policy, the Washington research group that produced the report, in an interview. But it's clear, he added, that dozens--perhaps hundreds--of schools will fail to meet goals established in states that assumed that schools would be ready to make dramatic increases in student achievement in the years closer to the deadline.