The test results are in... and they're not so good. On Wednesday, the College Board reported that SAT reading scores for the graduating class of 2011 are the lowest since 1972, the first year for which comparisons are available. The average reading score was 497 on the 200-to-800 point scale, down 33 points from 1972, and three points from 2010. What's behind the decline? Here, four theories:

1. More students are taking the test
According to the College Board, for the first time ever, more than half of this year's graduating seniors took the SATs, up from 47 percent in 2010. "As more students aim for college and sit for the exam, scores decline," says Stephanie Banchero in The Wall Street Journal. Still, "the good news is we have more students thinking about college than ever before," says James Montoya, a College Board vice president.

2. And they're a more diverse lot
"Devastating" gaps exist between various socioeconomic groups' academic opportunities, Montoya says, and this year, 27 percent of test-takers came from homes where English is not the only language spoken, up dramatically from 19 percent ten years ago. "About 30 percent of those who took the SAT were black, Hispanic or American Indian, groups whose scores have stubbornly remained lower than those of whites and Asians," says Tamar Lewin in The New York Times.

3. No Child Left Behind screwed everything up
The oft-derided 2002 law that put an emphasis on standardized testing at the state level may be costing students some of the "higher-order thinking skills" measured by the SAT. "We have score inflation on state tests, because that's what teachers are drilling, and lower performance elsewhere," said Bob Schaeffer with the advocacy group FairTest, as quoted in The Washington Post.

4. It's just a fluke
"Whether the decline in SAT reading scores reflects a broader pattern is unclear," says Michael Alison Chandler in The Washington Post. "This year's reading scores on the ACT, a rival college admissions test, held steady."