For 51 years, Catherine Mack has lived in a four-bedroom house in Haddon Township, N.J. Even at age 96, she has no intention of leaving.

Joining other older adults at a nearby retirement community doesn’t appeal to her, although the facility is attractive and has a great reputation.

“I think in a place like that, life is restricted,” Ms. Mack explained. “You eat at a certain time, and you’re always around other people. I am more on the side that I like to do what I want to do when I want to do it.”

So this independent woman instead selected to get services at home from the retirement community’s “C.C.R.C. without walls” program.

Only a dozen continuing care retirement community — C.C.R.C. — programs like this exist across the country, mostly east of the Mississippi. But several more are under development, and experts believe the concept may be poised to expand more broadly in the years ahead.

How does it work?

In traditional continuing care communities, members pay a substantial entry fee ($250,000 and up) and monthly fees (typically $2,000 to $4,000 a month) for housing, with a lot of on-site amenities and a guarantee that assisted living and nursing home care will be available, if needed. The model is “come to us and you’ll get what you need — all in one place.”

In a continuing care program without walls, members also pay an entry fee ($20,000 to $70,000) and monthly fees ($250 to $800) and receive a similar guarantee of lifelong care, with a twist. The main focus of these programs is helping people stay healthy and independent in their homes for as long as possible. This model can be summed up as “let us bring what you need to you — or find a way to make it easy for you to get it.”

With retirement nest eggs shrunken because of the recession, and 90 percent of older adults indicating they want to age in place at home, “this was something we feel makes a lot of sense,” said Larry Yachcik, president of Porter Hills Retirement Communities and Services in Grand Rapids, Mich., one of the nation’s newest providers of such services.

Armen Oumedian, 89, who joined soon after the Porter Hills program opened in July, said, “I see this as a tremendous way to lift a responsibility off the shoulders of my family and make it so I can live a continuing life in the community.”

“It’s a great comfort, a great security, to know you’ll be taken care of and that you’ve made all the necessary arrangements,” he said.

Programs vary, but all rely on care coordinators to get to know members, understand their living situations, keep an eye on their physical health, and handle problems that come up.

Five years ago, when Ms. Mack had several serious medical problems that put her in the hospital for nearly seven months, “my care coordinator had her finger in the pie all the time,” she said. “If there was any little bump in what I was going through, she was right there, trying to fix it.”

Her daughter, also named Catherine Mack, 61, said, “It was an unbelievable comfort to us.”

Most programs cover the full cost of any in-home care that’s needed (home health care nurses or companions who help older people bathe and dress), as well more intensive long-term services (rehabilitation, assisted living or nursing home care) at no extra cost and with no waiting period.

After Marjorie Rittenhouse, 77, of Painesville, Ohio, came home after foot surgery several years ago, “someone was there 24/7 for seven days,” she said. “It was all arranged — and I didn’t pay anything.”

At Kendal at Home, in Westlake, Ohio, (launched in 2004), where Ms. Rittenhouse belongs, members also get a thorough fitness assessment, a home assessment to identify changes needed to age in place safely (like grab bars in the bathroom and extra lighting) and a home maintenance assessment to figure out what work needs to be done on a house or an apartment (a new furnace? turn up the temperature in the fridge?), said Lynne Giacobbe, executive director.

Tiered plans with varying levels of benefits are common. The most expensive cover services 100 percent; others can require a co-payment of up to 30 percent for assisted living or nursing home care. Operators say that the most expensive plans are the most popular, because people want the extra protection. When long-term care is necessary, it’s typically provided in the assisted living or nursing home section of a continuing care retirement center with which the program is affiliated.

All programs require that members have health insurance, whether from a private employer or Medicare with supplemental coverage included. If someone has long-term care insurance, rates are discounted. Programs will arrange in-home meals, physical therapy or transportation to medical appointments, as medically required.

Most let members go to health clubs and social events at associated continuing care retirement centers without charge.

So what’s the catch, you’re thinking?

Here’s the most important one: To join, older people have to be healthy and functioning at a high level independently. If you’ve got any kind of serious chronic health condition, you probably won’t qualify. That’s the only way programs like this can work: by excluding people with immediate health needs, including any indicator of dementia, and doing everything possible to make sure that people stay healthy and at home as long as possible instead of needing institutional care.

“The screening process is much more stringent than for people who move to our campuses,” said Victor Amey, president and chief executive of Cadbury Senior Services, which operates two continuing care retirement centers, as well as the program that serves Ms. Mack in Haddon Township.

In checking around, I found one exception to this general rule. The Alexian Live at Home Program in Chattanooga, Tenn., which began in 2002, will take people with mild dementia or cognitive problems who are otherwise in good health for its “bronze” plan, which pays 70 percent of the cost of in-home services but excludes assisted living or nursing home care.

The very feature that makes these kinds of programs so attractive – relatively low entry fees and reasonable monthly fees – could become a problem if more members than expected become ill and need care, and available funds aren’t sufficient. So have a lawyer look over the contract carefully to see what rights you have if services are denied or withheld. I didn’t hear about this problem, but it’s a possibility worth your attention.

Why aren’t there more programs of this kind?

“The focus of the senior housing industry has been on bricks and mortar,” not community-based services, said Stephen Maag, director of residential communities for LeadingAge, an industry association. “But we’re now getting a recognition there is a significant market out there of people we haven’t been serving, and that represents an opportunity.”

In some states, laws that govern continuing care retirement centers didn’t allow for these kinds of services and had to be changed. Efforts are under way, or have already succeeded, in California, Connecticut, Florida, New Hampshire, North Carolina and Virginia, according to a paper on the centers that Mr. Maag prepared in February.

Would a “C.C.R.C. without walls” program appeal to you? Do you know of anyone who has had a negative experience in these programs? What concerns do you have, and what questions would you like answered?