Among Washington’s most sacred of cows is the Head Start program, which has enjoyed support from across the political spectrum since its inception in 1965. Today, even otherwise poles-apart politicians like George W. Bush and Barack Obama agree that spending billions of tax dollars on Head Start is a good thing. Bush and Obama also agree on something else about Head Start — taxpayers need not be told that it is a colossal failure, a fact officials have known since at least 2006.

Washington has spent hundreds of billions on Head Start as a Great Society program designed to ensure that at-risk kids from poor and minority communities start school on an equal footing with those from other neighborhoods. For years, nobody questioned Head Start’s efficacy, but in 1997 a Clinton administration advisory panel recommended that funding be approved for the Head Start Impact Study. Unlike sporadic previous efforts to measure Head Start’s effectiveness, the HSIS was “to be the best that evaluation science could offer to determine the degree to which Head Start worked, for whom, at what points in schooling, and for what outcomes,” according to panel member Russ Whitehurst, now at the Brookings Institution. A contract for the study was issued in 1998 by the U.S. Department of Health and Human Services, which manages Head Start.