The most pressing global problems simply won't be solved without the participation of women. Seriously, guys. On a trip to Afghanistan in the summer of 2009, not long after my appointment as the U.S. State Department's ambassador at large for global women's issues, I stopped for dinner with a group of Afghan women activists in Kabul. One woman opened our conversation with a plea: "Please don't see us as victims, but look to us as the leaders we are."

Those words have stuck with me as President Barack Obama's administration has endeavored to put women at the heart of its foreign policy. For generations, the United States too often viewed the world's women as victims of poverty and illiteracy, of violence and seemingly unbreakable cultural traditions -- essentially, as beneficiaries of aid. Women's issues existed on the margins, segregated from the more "strategic" issues of war, peace, and economic stability. Now, in a time of transformative change -- from the rise of new economic powers to a growing chorus of voices against repressive regimes in the Arab world -- promoting the status of women is not just a moral imperative but a strategic one; it's essential to economic prosperity and to global peace and security. It is, in other words, a strategy for a smarter foreign policy.

In the past, U.S. diplomacy and development efforts were conducted in a manner that was gender neutral at best. The United States regularly supported peace talks that left women out of negotiating rooms and treaty documents, an omission that weakened the chances of forging durable peace agreements. The country designed development programs without consulting women or considering the crucial role they played, whether it was agricultural training initiatives that targeted men even though women often represented the majority of small farmers, or building wells in areas where women could not go, never mind that women were the ones responsible for fetching water.

As a growing body of research shows, however, the world's most pressing economic and political problems simply cannot be solved without the participation of women. That's why Secretary of State Hillary Clinton is working to ensure that advancing the status of women and girls around the world is fully integrated into every aspect of U.S. foreign policy. As of this spring, with the release of a first-ever secretarial policy directive on gender, advancing the status of women and girls worldwide is officially a requirement in every U.S. diplomat's job description. As Clinton said in March, the United States will use "every tool at our disposal" to support this crucial cause.

Why? This is, as Clinton has called it, a "Full Participation Age," an era when information transcends borders, opinions and ideas scale firewalls, and the world can no longer afford to leave millions of women out of the global community. It's no coincidence that those countries that deny women basic human rights are some of the poorest and least stable. According to the World Economic Forum, countries where men and women are closer to enjoying equal rights are far more economically competitive than those where the gender gap has left women and girls with limited or no access to medical care, education, elected office, and the marketplace.

As much of the world struggles to climb out of recession, the economic participation of women and their enhanced efficiency and productivity are essential to recovery and growth. Goldman Sachs researchers, for example, found that closing the gender gap between male and female employment would be a powerful engine for global growth, even in the United States and the eurozone, where it could boost GDP by billions of dollars. In fact, the Economist has reported that the increase in employment among women in developed countries contributed more to global GDP growth than China as a whole in recent years. Yet many women still lack access to capital, credit, and training. Laws prevent them from inheriting or owning land. Cultural traditions inhibit women's participation in the formal economy. In the agriculture industry, to take one example, the UN Food and Agriculture Organization estimates that if women farmers were provided the same access to seeds, fertilizer, and technology as men, they could improve their yields by 20 to 30 percent and reduce the number of undernourished people in the world by 100 million to 150 million.

This is not just about the economy, though; it's also about global security. In the 1990s, nearly half of all peace agreements failed within the first five years, according to the Human Security Report Project. These deals are generally struck by a small number of male military and political leaders shielded from war's impact on daily life. Women, meanwhile, endure much of the residual violence and poverty caused by armed conflicts, and they bear much of the burden of rebuilding families and communities. They are often excluded, however, from both the negotiating table and the governments charged with sustaining peace. Less than 8 percent of the hundreds of peace treaties signed in the last 20 years were negotiated by delegations that included women, and according to the World Economic Forum, women hold less than 20 percent of all national decision-making positions.

Excluding women from these negotiations exacts a measurable cost. In 1994, for instance, women were far from the minds of the men who, with U.S. support, signed the Lusaka Protocol that ended two decades of civil war in Angola. The commission established to implement the protocol consisted of 40 men -- and not one woman. Women were also left out of demobilization programs for ex-combatants because the definition of "combatant" did not consider the thousands of women who had been kidnapped and forced to work as military cooks, messengers, or sex slaves. Demining efforts focused on roads and failed to target the fields, wells, and forests where women grew crops, fetched water, and gathered firewood. And following a conflict in which rape was used as a weapon of war, the male negotiators granted each other amnesty for the crimes they had committed against women. Just four years later, war began anew.

We do not want to see history repeating itself. Last December, the administration launched a national action plan on women, peace, and security, which expands U.S. efforts to include women in conflict prevention, peace negotations, and reconstruction. Still, the exclusion of half the world's population continues to threaten many countries. In Egypt last year, women marched on the front lines of the protests, often leading their fathers, brothers, and husbands into Tahrir Square. A year later, the courageous women of the Arab Spring fear not just that progress on women's rights will halt, but that the rights they currently enjoy will be rolled back.

Or consider Afghanistan. Although the number of women attending school and serving in parliament and on local peace councils has increased dramatically over the past decade, the country remains the world's most dangerous for women in terms of health, violence, and lack of economic resources. The United States must continue to insist that insurgents who want to reconcile must commit to protecting the rights embedded in the Afghan constitution -- including those for women. There may be some who, in the interests of getting a deal done, consider women's rights negotiable. But this is a red line that cannot be crossed; any peace that is made by excluding more than half the population is no peace at all and will not last.

In all circumstances, and especially in the most challenging ones like those in Afghanistan, the United States must remain a vital voice for women and girls not just because it is the right thing to do but because it is the smart thing to do. Give a small-businesswoman access to capital and training, and she can become a powerful contributor to GDP growth. Include women in governments and peace talks, and they can help ensure that ministries are better run and peace agreements are sustained. Educate a girl, and she will be more likely to raise healthier and more educated children -- and end the cycle of poverty.

Secretary Clinton has championed the use of "smart power": deploying all the tools at America's disposal to advance national interests -- not just military might, but also diplomacy, development, and America's enduring values. Advocating for women's full economic, social, and political participation around the world is one of the most potent weapons in America's smart-power arsenal. And it's one we shouldn't even hesitate to unleash.