Six years after the No Child Left Behind Act became law, many states still haven't completed one of its most important tasks: establishing a testing system that meets the law's requirement that they track all students' progress toward proficiency in reading and math. Although the progress has been slow, U.S. Department of Education officials and state leaders suggest that states have made adequate strides in meeting the formidable challenge of dramatically increasing the amount of testing and creating new exams that measure the success of students with disabilities. One critic of the pace said that states should be much further along in complying with the testing rules. The 1994 version of the Elementary and Secondary Education Act, of which the NCLB law is the latest version, required states to assess students in key subjects at least three times during their K-12 careers--thus pointing the way, that critic suggested, to the more extensive NCLB mandate. The approval status of a state's testing plan has become especially important recently because a state must have such approval to participate in two federal projects intended to give states greater flexibility in implementing the NCLB law.