Federal regulations have opened a door that allows schools to get credit under the No Child Left Behind Act for students who take longer than four years to earn a high school diploma. That option worries some education advocates, who fear it could relieve valuable pressure on high schools to graduate students on time. Under the law's accountability provisions, students who don't graduate in four years count against schools' graduation rates. Many educators have complained that such an approach punishes schools that go the extra mile to keep students from dropping out or to lure back those who have left school. Several states have now applied for federal permission to use extended-year rates, according to the U.S. Department of Education. Only one state, Washington, has permission to use them, as the result of a waiver granted in 2005.