When the U.S. population officially hit the 300 million mark last October, there weren't any celebrations. Most news organizations took note of it and moved on. Environmentalists and other liberals crabbed about having more people around to consume precious resources.

Fortunately, not everyone harbored such a jaundiced view of this milestone.

"We should celebrate more people, not bemoan population growth," said Dr. Allan Carlson, founder of the World Congress of Families. "With birth rates plummeting in the industrialized world, America's population growth is a hopeful sign."

He's absolutely right. When societies forget the fact that families are the very basis of civilization - that they are, in essence, society in a microcosm, reduced to its most fundamental building block - it's from that point that they begin a slow but unmistakable decline into helplessness and despair. That's why the World Congress is sounding the alarm - most notably at the May 11-13, 2007 " World Congress of Families IV," to be held in Warsaw, Poland. It's billed as "the world's largest conference of pro-family leaders and grass-roots activists." And that's exactly what we need - an unprecedented push from the pro-family forces - if we're to have any hope of solving a problem of this magnitude.

For the time being, we're doing OK fertility-wise here in the U.S. Our fertility rate is 2.11 births per woman, right at what demographers consider replacement level. But other parts of the world are in serious trouble. According to the World Congress, the overall fertility rate for Europe is only 1.3. In Italy, it's 1.2. In Spain, 1.1.

These kinds of numbers, quite frankly, spell doom for a country if left unchecked. There's a reason that columnist Mark Steyn, who spoke at The Heritage Foundation in January, calls his latest book " America Alone" - we're about the only Western nation not in the throes of what he calls a "death spiral." Consider Russia, with a fertility rate of 1.2. Britain is also below replacement level, at 1.6 births per woman. So is France, at 1.89 - and a third of those births are not of the French, but of the new Muslim community that has moved into the country. Plainly put, France will very soon become a country that is not French at all.

It seems ridiculous to have to point out something so obvious, but a society that ceases to reproduce is on the road to extinction.

"How can a declining population maintain a nation's infrastructure?" Carlson asks. "Who will man Europe's factories, farms and armies? Who will pay the taxes for essential social services? A birth dearth provides far more challenges than a population explosion."

No wonder governments are beginning to take notice - and take action. Russian President Vladimir Putin, for example, has adopted a policy that offers a $110 monthly stipend to families that have a second child. According to Don Feder, director of communications for the World Congress, "Stay-at-home moms would receive 40 percent of their former salary, and families with two children would get a direct payment of $9,000." Other countries are offering financial incentives for couples to have more children.

It's an open question whether this strategy will work, especially when you consider how long we've been listening to the selfish, anti-population propaganda of the "population bomb" crowd. Our modern world seems so steeped in narcissism and so averse to welcoming new life that it likely will take more than money to stem the tide.

But despair solves nothing, which is why the World Congress of Families is bringing many of the best pro-family minds together - to chart a path out of what Feder has called "the depths of demographic winter." Among them will be The Heritage Foundation's own Pat Fagan, whose pro-family research has illuminated the debate for a decade - and helped many people to better understand the irreplaceable role the traditional family plays in our society.

If you'd like to help spread the pro-family message, I urge you to take some time to acquaint yourself with the principles espoused by the World Congress. Check out Allan Carlson's book "The 'American Way': Family and Community in the Shaping of the American Identity." He opens with an interesting overview of President Theodore Roosevelt's pro-family policies. It's a subject the president was refreshingly blunt about:

"I do not wish to see this country a country of selfish prosperity where those who enjoy the material prosperity think only of the selfish gratification of their own desires and are content to import from abroad not only their art, not only their literature, but even their babies."

If Europe is ever to pull itself back from the brink - and if the United States hopes to avoid a similar fate - we need to realize that true prosperity can't exist without families. Indeed, a world without babies is flirting with the most serious form of poverty there is.

Rebecca Hagelin is a vice president of The Heritage Foundation and the author of Home Invasion: Protecting Your Family in a Culture that's Gone Stark Raving Mad.