Eric Klinenberg, Penguin Press, 273 pages, $27.99

"You need an apartment alone even if it's over a garage," declared Helen Gurley Brown in her 1962 bestseller "Sex and the Single Girl." To Brown, who went on to edit Cosmopolitan magazine, the benefits of solo living were innumerable: It afforded the space to cultivate the self, furnish the mind and indulge in sexual experimentation.

Sensational at the time, Brown's counsel seems sensible now. Certainly both sexes have taken it to heart, marrying later, divorcing readily and living alone in larger numbers than ever before. In the United States more than half of all adults are single and roughly one out of seven lives alone. Yet little is known about the wider social effects of this unprecedented boom, writes Eric Klinenberg, a sociologist at New York University.

Klinenberg parts with those who see the rise of solo living as yet another sign of the decline of civic society. Solitary living need not mean solitude. The author offers evidence that people who live alone are often more socially active than their cohabitating peers. The "communications revolution" has allowed more people to have a social life from the comforts of home, and cities with high numbers of singletons enjoy a thriving public culture of bars, cafes and restaurants. Urban officials are now eager to lure professional singles in the hope that they will stimulate the local culture and economy.

Living alone is easy enough for the young and solvent; less so for the elderly, frail and poor. Klinenberg came to this story while working on a book about the lethal Chicago heat wave of 1995, when hundreds of people died alone. He looks wistfully to the Scandinavian countries, where generous social-welfare benefits and communal urban design allow more people to live alone together. He calls for "bold policy initiatives" such as more assisted-living facilities. "We'll need them," he adds, "since so many of us will be living alone."

THE ECONOMIST