From the New York Times report on this study:
In both reading and math, the study determined, test scores have gone up somewhat, as each class of students outdoes its predecessors. But within grades, students have made less academic progress during the school year than they did before No Child Left Behind went into effect in 2002, the researchers said.
That finding casts doubt on whether schools can meet the law's mandate that all students be academically proficient by 2014. In fact, to realize the goal of universal proficiency, the study said, students will have to make as much as three times the progress they are currently making.
No Child Left Behind was originally passed with bipartisan support, but many Democrats have felt that the implementation has been faulty, concentrating on penalizing schools rather than providing the support to improve public education. Many liberals fear that the real goal of the Bush administration is to force schools to fail in order to increase use of voucher systems to provide tax money to religious schools.