For nearly a decade, Seven Eggs has stayed with his son in the town of Crow Agency, on southeast Montana's Crow Reservation. Their faded green house, built roughly 40 years ago by the U.S. Department of Housing and Urban Development, is deteriorating. The siding is peeling, the roof leaks; one bathroom is a lightless construction zone with unfinished wiring and a gap in the shower where framing shows through. Black mold grows on the walls, and though Seven Eggs scrubs it away with bleach, it returns, with a heavy scent that lingers in the back of the throat.

Seven Eggs (his Crow name, which he prefers to Ira Bad Bear, his American one) spent two years as a U.S. Army combat engineer in Vietnam. "It was a great accomplishment for me," he says. But since returning in 1971, he has suffered from post-traumatic stress disorder and rarely owned a home.

In his first years back on the reservation – wrestling with anxiety, alcoholism and nightmares that still steal his sleep – he stayed with his mother or camped on the nearby prairie. "I felt safer out there," he says. "I was kind of expecting trouble from every corner." He later married and lived with his wife's family until the couple bought their own home. But once they separated, Seven Eggs moved into a tepee behind the house where he now lives. When the snow began to fall that first winter, his son invited him to stay inside as a guest. But the arrangement is tenuous: His son's relatives own the house, making it hard for Seven Eggs to apply for tribal grants to repair it, and leading him to wonder when he will have to move again.

One Crow official calls Seven Eggs' situation "invisible homelessness." In urban areas, folks often end up in shelters or on the streets, where they are easily recognized. But in Indian Country, where housing shortages are common and shelters in short supply, families cope by sharing spare rooms, couches and floor space. This is one reason why many Native vets like Seven Eggs have slipped through the cracks of HUD-VASH, an otherwise effective federal program that aims to end veteran homelessness.

Revived by President George W. Bush in 2008, HUD-VASH is now the centerpiece of an Obama administration push to end veteran homelessness by 2015. But red tape prevents many veterans in Indian Country from participating, even though in 2010, Native American vets were significantly more likely to be homeless than their white, non-Hispanic counterparts. While Native Americans enlist at a rate generally twice that of other races, they return home to above-average disability rates and the lowest incomes.

All of this means HUD-VASH is least available to those who most need it, argues Zoe LeBeau, a Minnesota-based housing consultant who has long fought to bring the program to reservations. "VASH vouchers are the number-one tool we have to stabilize housing for veterans," she says. "And tribes don't have access to them."

Administered by HUD and the Department of Veterans Affairs, HUD-VASH provides Section 8 housing vouchers to chronically homeless veterans, ensuring they spend no more than 30 percent of their income on rent. Since many recipients suffer from addiction and other ailments, the rental funds are paired with VA clinical and social services. Backed by $425 million in housing funds to date, this model has helped reduce veteran homelessness by over 24 percent since 2009, while overall homelessness declined just 5 percent. But of the roughly 58,000 vouchers awarded so far, only 600 have gone to Native Americans.

The main barrier is the 1996 Native American Housing and Self-Determination Act (NAHASDA), which controls most federal housing funds distributed to tribes, explains Deana O'Hara, a senior adviser in HUD's Office of Native American Programs. A conflict between that law and the Housing Act of 1937, under which HUD-VASH is administered, prevents veterans from using vouchers for federally subsidized houses on reservations. Most reservation housing is federally subsidized.