In "Bowling Alone," Harvard political scientist Robert D. Putnam crunches numbers to indicate that by just about every conceivable measure -- from voter turnout and Sunday school attendance to the habits we report, the opinions we express and the fears we confide to pollsters, social scientists, people meters, time diaries and the "DDB Needham Life Style" archive -- we are less inclined than we used to be to leave the house for any reason except work. Nor do we invite folks over as often for games of bridge, hands of poker, kinky sex or plotting coups. Since 1968, "civic engagements" of every sort have plunged by 20 to 40 percent across the American board, irrespective of race, creed, class, income, marital status and erogenous zones. Fewer of us trust our neighbors or our institutions, volunteer our time or energy, pitch in or help out. Whether for meetings of the school board, the union local, the Odd Fellows, the Boy Scouts or Hadassah, we are failing to show up. We even write fewer letters to editors and members of Congress.

Everywhere that Putnam looks, he sees a rising tide of apathy and a downward trajectory to "malaise." In this unbrave new Malaisia, it's not just that we are a third less likely to attend town meetings and donate blood than Americans were in the '60s, or that we give a smaller percentage of our income to charity -- that we are less Masonic, less Jaycee and less in league with women voters. If formal religious worship has fallen only 10 percent, participation in the social life of the church or the synagogue, from Bible studies to potluck picnics, has dropped by a third since the '60s and a half since the '50s. The figures are likewise down, by 10 to 20 percent in the past two decades, for fishing, hunting, camping, skiing, jogging, swimming, tennis, softball, football and volleyball. All the women playing sports (after Title IX) and all the children playing soccer (now that there are college scholarships), all the 12-steppers and all the New Age encounter groupies, don't make up for huge defections elsewhere in the culture. More than twice as many adults have dropped out of league bowling in the past 20 years than have ever been in all of the self-help programs combined, including Weight Watchers and Alcoholics Anonymous.

While the gross numbers may be up for memberships in professional societies, the proportions are down, considering how many more professionals there are now. (For instance, the ratio of lawyers to the rest of us has doubled since 1970, maybe because the rest of us no longer trust anybody unless we have a legal contract plus our personal pit bull. But the American Bar Association's "market share" of this excess fell a third in the same three decades.) The picture's even bleaker if we look for members who do more than merely pay their dues. And don't tell me that you're a card-carrying member of the ACLU, the Children's Defense Fund, Greenpeace and Amnesty International. So am I. And neither of us has gone to a single meeting of any of these organizations. Instead, we've written a check for a lobbying group with a professional staff in Washington or New York. We could be living right next door to each other and not know that we are "members" of the same interest group. We are, instead, "consumers" of a direct-mail cause.

In other words, like a bunch of hippies, we are dropping out. Unless, that is, we happen to have been born between 1910 and 1940 -- in which case we belong to Putnam's "long civic generation" and can be counted on to do a lot more good than those narcissistic baby boomers, who, when they aren't pushing money through their modems, are probably watching soft porn on cable television. When handing out blame for our antisocial funk, Putnam assigns the biggest chunk to self-involved boomers, the next biggest to time-stealing television and smaller percentiles to mobility and urban sprawl (relocation, the lonely commute), financial anxiety (fear of falling, downsized syndrome), workplace blues (what we used to call the alienation of labor), working mothers (there goes the PTA) and a general agnosticism or paranoia about reality itself. He sees little evidence that the behavior of government, the decline of the traditional family or the advent of rap music and the Internet has much to do with it. He should at least have mentioned the designated hitter in American League baseball.

Of course, Putnam is guessing. And so will I.

It's always fun to beat up on boomers with a stick. And they will certainly be sorry. They'll be sorry, first of all, because joining a group is good for everybody. "Civic virtues," Putnam notes, tend to "cluster." If you belong to a service club, you're more likely to volunteer in a meals-on-wheels or reading program, contribute to a library building fund and vote for a school or sewer bond. Thus, as if by shrewd investment, a single act of wandering into a "domain of sociability" multiplies to help create the social capital that trickles down to benefit education, health, seniors, children and the lonely, needy and strange. (My favorite odd datum in this fact-filled book is that people who listen to lots of classical music are more likely to attend Cubs games than people who don't.)

The boomers will be even sorrier, second of all, because joining is better for body and soul. Medical studies suggest it's healthier to get out of the house: "As a rough rule of thumb," Putnam tells us, "if you belong to no groups but decide to join one, you cut your risk of dying over the next year in half. If you smoke and belong to no groups, it's a tossup statistically whether you should stop smoking or start joining."

Maya Angelou reads from "The Heart of a Woman"