Middle-Class Communes

At 75, May D'Marie has visited enough retirement homes to know that she never wants to live in one. "They're boring," she says. "Everyone is the same age practically. And even the elevators move slowly." But she also doesn't want to live alone, doesn't have family in her area and doesn't want a roommate. That seemed to leave the retired librarian with no options--until she heard about a new community being built near her in Sacramento.

At Southside Park Cohousing, D'Marie now shares three meals a week in a central dining hall with 65 other residents of all ages. Her apartment,...