Sixty years ago, America emerged from World War II triumphant, yet facing both a new adversary (the Soviet Union) and a hostile ideology (Communism). Rising to the challenge, the postwar statesmen devised efforts like NATO, the Marshall Plan, and the Berlin Airlift. These undertakings were bold and imaginative in design and audacious in scope and ambition. Their efforts at once advanced America’s strategic interests and gave expression to the best of our national ideals. They helped America win the Cold War.

To date, the Bush administration has failed to meet the challenges and opportunities of the post-Cold War, post-9/11 world with programs of comparable depth or imagination. Though the administration has not mobilized to seize the opportunities of our moment, much of the rest of America has. In the past decade, America has seen an explosion of non-governmental organizations (NGOs) and charitable giving, making it clear that there is a deep reservoir of goodwill and desire to be of service among Americans.

Leaving the presidency at the ripe age of 54, Bill Clinton determined that he would devote his post-presidency to mining this reservoir, with the aim of tackling some of the most daunting problems of our age.

This is a very good thing. Mr. Clinton’s talents, his intellectual energy, his imagination, and his star appeal remain prodigious. And so are the problems that we face. In “Giving: How Each of Us Can Change the World” (Knopf, 256 pages, $24.95), his third and latest book, Mr. Clinton issues a call to action. He wants all Americans to enter the fray, to become citizen activists, giving money, time, things, skills — anything they can muster — to engage challenges ranging from dirty beaches to illiteracy, from global warming to AIDS in Africa.

We learn of scores of organizations — some big, some small; some global, some very local — working on these problems. We also meet a streaming procession of engaged citizens. Many are titans of industry, media, or finance: Everyone from Oprah Winfrey to Magic Johnson to Sandy Weil and Warren Buffet — and dozens of their ilk — is profiled.

But the book gives equal space to people more representative of the rest of America. It is in considering their activities that “Giving” is most inspiring. We come to know Oseola McCarty, an African-American cleaning lady from Hattiesburg, Mississippi, in her late 80s who had lived very modestly, only to pass on most of her life savings ($150,000) to endow a scholarship program at a local University because she wanted young people to “have the educational opportunities she’d missed.” Sheri Saltzberg and Mark Grashow of New York had recently retired from public health administration and teaching when they started an NGO to provide supplies to schoolchildren in Zimbabwe. In a span of a few years, they sent over more than 150,000 books, bicycles, clothing, sports equipment, and more to 35 schools to aid the beleaguered children of that tragic country. These “everyday person” profiles are compelling because they force the reader to consider what he or she can do as well.

“Giving” also makes it clear that, for those inclined to engage, there is no shortage of worthwhile organizations from which to choose, and Mr. Clinton breezes through a cornucopia of worthy NGOs. On the whole, the book is well-written, crisp, and nicely paced. At times, though, because of the sheer breadth of groups and people introduced, it reads something like a directory or a catalog of charitable organizations. In places, I found myself wanting to learn more about a specific group, its mission, its founder, a person affected by its work, or the reasons why it is impactful. In the end, though, this approach has the merit of providing the no doubt intentional impression that Americans are by and large a generous, innovative, and engaged people, and there is reason to feel hopeful about the challenges we face and our ability to meet those challenges.

Mr. Clinton misses a good turn by not mentioning our soldiers, their families, or the many and extraordinary organizations and efforts burgeoning all over America to assist them. In addition, I would have loved for him to have elaborated on his overarching visions for solving the great problems he lays out (for example, climate change and global poverty). Without strategic cogency (a set of aims, a budget and timeline to get there, and the policies and alignment of actors to advance the strategy), the patchwork of efforts highlighted in “Giving” are likely to do much good, but are unlikely to solve these problems in a viable, sustainable way. Mr. Clinton highlights the importance of government in leading, alludes to the Millennium Development Goals, and gives us ingredients for policy prescriptions. He is at his best when wading into policy; the Clinton magic is at full throttle, for example, when talking about harnessing capital and consumer power to create markets for the public good.

To meet the great challenges of our time, government must lead, and must summon the entire American citizenry to be a part of the solution; with a role for the private citizen acting on his or her initiative, yes, but ultimately with a concerted national strategy and shared national sacrifice. In the post-Cold War, post-9/11 world, our leadership has still not put forward the programs or ideas necessary for us to meet the great challenges of our time. Mr. Clinton is uniquely able to inject such ideas into our discourse, and I hope that he will lay them out in other forums.

“Giving” is a paean to the many Americans who have not sat idle, but who have sprung forward, with compassion, imagination, will, and decency, to tackle the world’s most daunting problems — whether mile by mile or inch by inch. For helping to lead them, for cheering them on, for using his extraordinary talents and the bully pulpit of his ex-presidency to notice them, and for summoning the rest of America to join their ranks, Mr. Clinton is to be highly commended — and his book should be widely read.

Mr. Behrman is author of “The Most Noble Adventure: The Marshall Plan and the Time When America Helped Save Europe.” He is also a fellow at the Carr Center at Harvard University and a Foreign Policy Fellow at the Aspen Institute.