(FORTUNE Magazine) – Most oldsters stay put until failing health forces them to forsake their residences. But some 250,000 relatively well-off Americans, worried that they won't find a decent nursing home when the need arises, aren't leaving matters to fate. While still in good health and typically in their mid- to late 70s, they have moved into one of a growing number of so-called continuing-care retirement communities (CCRCs). Prices at CCRCs range up to $648,000 for a luxurious two-bedroom apartment at resort-like Harbour's Edge in Delray Beach, Florida. For the up-front investment, plus a monthly charge that covers at least some dining room meals, a CCRC resident has guaranteed admission to health care facilities on the site or close by. For those requiring limited help, say, in bathing, the next stage is ''assisted living,'' followed by full-scale nursing home care. At some CCRCs the monthly charge jumps to full nursing home rates once you leave the ''independent'' phase in the apartment. But in the ''life care'' version of a CCRC, a uniform monthly charge -- subject to inflationary increases -- prevails throughout the community. In effect, the monthly charge for the apartments subsidizes the assisted-living and nursing home phases. Robert and Carolyn Browning (left) moved last April into Collington, a four- year-old, Episcopal church-sponsored life care community on 128 pleasantly wooded acres near Washington, D.C. Prices at Collington range from an entry fee of $59,860 for a person living alone in a studio apartment, plus $1,371 a month, to $174,450 for a two-bedroom apartment occupied by two, plus $3,067 a month. Entry fees are refundable on a sliding scale, diminishing to zero after 50 months of residence. If you pay an additional sum up front -- $31,890 for that two-bedroom unit -- your heirs, who otherwise get nothing after 50 months, can reclaim half the entry fee. CCRCs aren't worry-proof. About 40 have gone broke since the mid-Seventies. But Eric Belsky, an economist at the National Association of Home Builders, says, ''The Collington type of CCRC is much more sophisticated about pricing than the ones that had trouble in the Eighties.'' The best bets are CCRCs with strong balance sheets and an imprimatur from the Continuing Care Accreditation Commission, a private organization in Washington, D.C. Living in the shadow of a nursing home can be depressing for still-active apartment residents. Bob Browning, a former naval architect, nevertheless answers ''absolutely'' when asked if he likes Collington. He says he got fed up with maintaining the Brownings' previous home in Annapolis, Maryland, and recalls how a doctor told him living in a retirement community was either jail or a cruise ship. Says Bob: ''This is a cruise ship.''