They may be the most low-profile participants in one of the 2000 Census' most high-profile trends. A small but growing number of Americans over age 65 now live as cohabiting couples, almost twice as many as a decade ago, census surveys show.

For older people, living together holds both emotional and financial attractions but requires shedding moral inhibitions ingrained in youth and, at times, dealing with the squeamishness of children and longtime friends.

Demographers expect the portion of senior couples who cohabit to grow dramatically in the 2010 and 2020 Censuses as baby boomers who rebelled in their 20s bring their attitudes into old age. For the swing generation of 60-and-overs captured in this Census, however, living together remains a liberating, if conflict-laced, option.

"We grew up in a different generation," said Ruth Nippe, 79, who has lived with partner Jim McDaniel, 81, in Mission Viejo, Calif., for four years. "I came from a small town in Nebraska. I would have been ostracized for sure for living this way. I guess I used to care more what people said."

The 2000 Census data released so far shows that unmarried-partner households overall increased 72 percent in the past decade. Age-specific data will come later, but a clutch of other Census surveys suggests that seniors, though constituting only a drop in the pool of cohabitants, may have met or outpaced that growth rate.

According to the Census Bureau's annual Current Population Survey, households made up of opposite-sex senior couples rose 46 percent between 1996 and 2000, a bigger jump than that of their middle-aged counterparts. Other reports fold in same-sex couples, showing the number of senior cohabitants rising 73 percent between 1990 and 1999, from 127,000 to 220,000.

Though couples' reasons for living together can be as idiosyncratic as relationships themselves, researchers link the shift to other social changes.

Higher divorce rates and longer life expectancies, especially for women, mean the population of single seniors is growing rapidly, sociologists said. For younger couples, marriage often is linked to the prospect of parenthood; older couples typically are beyond this stage in life. Though eager for love and companionship, they may be skittish about formal ties.

Researchers say older women, too, can be reluctant to re-up for marriage if they associate it with traditional gender roles played out in earlier relationships.

As potent as the emotional issues can be, pragmatism, not romance, often governs whether those older than 60 live together instead of getting hitched. Cohabitation, like marriage, allows older couples to share expenses, a crucial concern to those living on fixed incomes as life spans extend.

Not marrying, however, means couples do not take on the financial obligations of each other's long-term medical care or intermingle their retirement benefits. Such practicalities have kept Darlene Davis, 61, from marrying her partner of 17 years, Cary Cohen, 63. If the Norfolk, Va., pair wed, she would lose military benefits and insurance from her second marriage, which ended long ago with her husband's death. "We were not brought up to live in this position, but with our lives such as they are, we just can't afford to give up my medical coverage," Davis said.

While cohabiting seniors can -- and often do -- expressly provide for each other in their wills, unmarried partners do not have the same claims as spouses in many states. Many couples say they have left late-in-life relationships unofficial to avert conflict between the surviving partner and relatives.

"We didn't want to tie up our estates," Nippe of Mission Viejo said. "At our age, we have to think about when one of us isn't going to be here. Even though I'm very good friends with his kids, I wouldn't be comfortable if they ended up owning half of my house."