Besides appealing to seniors, NORCs also attract much younger residents, from 20-something singles to beginning families.

Jacob Goldman, president of LoHo Realty Inc. on Manhattan's Lower East Side, said Co-op Village, a NORC, draws active retirees downsizing from the suburbs and young people who want digs. near hip-and happening hangouts.

Five years ago, the development began allowing residents to sell apartments on the open market, and since then, prices have doubled. A one-bedroom co-op today starts at $400,000, said Goldman.

"Grandchildren are looking to buy apartments that their grandparents sold," he said.

Amy Schrift, 38, is a musician and single. Three years ago, she moved into Morningside Gardens because of its location - Manhattan's Upper West Side - and its diversity. Besides seniors, the complex has many families with children, she said.

"It's a total mix," said Schrift, "and I like the energy."