But despite getting more than $100 million a year in federal funding—including grants low-income students use to pay tuition—tribal colleges often have abysmal success rates. The average percentage of students who earn four-year degrees within six years (or two-year degrees within three years) at these schools is only 20 percent, according to a Hechinger Report analysis of federal graduation data—one third the national average and half the rate of Native students at non-tribal schools. These statistics only include first-time, full-time students, but at some tribal colleges, fewer than one in 10 of them ever finish.

"There’s not a lot of value for the student or for the tribes or the economies where they are," says Tom Burnett, a former Montana state senator who has been critical of tribal colleges.

The schools, which largely allow anyone to attend, say their poor outcomes are largely due to the many shortcomings students face before college even begins, including poor preparation in primary and secondary schools. Less than 70 percent of Native students graduate from high school, according to research by the U.S. Department of Education.

"The dilemma that we’re facing is we’re open admissions," said Thomas Shortbull, president of Oglala Lakota College on the Pine Ridge Reservation in South Dakota. "We do have a major problem with our students’ [preparedness]."

College accountability advocates are sympathetic to this argument—but only to a point.

"You can’t just say, 'That college has opened its doors wide and it has a low graduation rate, therefore it’s terrible,'" says Mark Schneider, vice president of the American Institutes for Research. "On the other hand, you can’t just say, ‘What do you expect?’"

Schneider and others argue that taxpayers spending tens of millions on tribal colleges and universities deserve to get more for their money.

"In higher education the federal government has essentially had a hands-off approach to their federal investment," says Mary Nguyen Barry, a policy analyst at Education Reform Now and co-author of Tough Love: Bottom-Line Quality Standards for Colleges, who says the government should try to help low-performing schools improve their graduation rates. If they can’t, Barry says, they should be cut off.

Struggling tribal schools would likely welcome extra support. Congress sets tribal college funding and is authorized by federal law to give schools a maximum of $8,000 per student. But in reality the schools get $5,850 per student on average. And that funding can be used only for Native American students; nearly a fifth of those enrolled don’t identify as Native. Howard University, a historically black college, by comparison averages more than $20,000 per student from the federal government.

"We want to see that the federal government is supporting our tribal colleges and universities as they are supporting any other minority-serving institution or state institution," says Victoria Vasques, former director of the White House Initiative on Tribal Colleges under President George W. Bush.