Women exercise power horizontally. I've said this often -- in speeches about leadership and at the Fortune Most Powerful Women Summit, an annual event that I chair. This horizontal slant spurs women leaders to reach beyond the jobs they're hired to do.

Want proof? In May, 40 top female executives in the U.S. -- all participants in the Fortune Summit -- spent two and half weeks mentoring rising stars from 24 developing countries. Avon CEO Andrea Jung hosted Zoe Ka Sali-Duma, a dynamic entrepreneur from Johannesburg, South Africa. Helene Gayle, CEO of CARE USA, hosted Dima Sharrafdeen, an amazing young entrepreneur from Beirut, Lebanon who runs a logistics company that does rescue and relief work in the Middle East and Africa. Other mentors who participated in the FORTUNE-U.S. State Department Global Women Leaders Mentoring Partnership include the top women at such companies as Avaya, Ernst & Young, ING, DuPont, Microsoft, KPMG, Merrill Lynch (MER), Wal-Mart (WMT), Exxon Mobil (XOM), JWT, Nielsen, Herman Miller, and law firms Skadden, Arps, Slate, Meagher & Flom and Fulbright & Jaworski. The photos shown here are from gala dinner in New York City, where we celebrated these mentoring duos.

Beyond the call

Many of this year's mentors went way beyond their duties. Time Inc. CEO Ann Moore took her mentee, Sun Chao, who is editor in chief of the China Economic Report in Beijing, to the swishy Time 100 party and invited all her fellow mentees who were working in New York City to her home for dinner. Other mentors - Solera Capital CEO Molly Ashby, Wells Fargo EVP Kathleen Vaughan, and Charlene Begley, the most powerful woman at General Electric (GE) - invited their mentees home for weekend stays.

At Xerox (XRX), mentee Alexandra Bulgakova from Russia accompanied chief Anne Mulcahy to an awards dinner in Manhattan. Alexandra and Xerox President Ursula Burns painted walls at a Rochester-area children's center and set up a carnival at a local hospital. At Avon, Zoe and Andrea Jung spent a day meeting with the marketing team on the company's South African market strategy -- and since Zoe once worked for Avon, she was the ideal mentee. "You want to learn as much from your 'mentee' as they learn from you," says Jung. "By the time you finish the relationship, I don't think you should know who is the mentor and who is the mentee."

How it started

Another mentor this year was Dina Powell, managing director and global head of corporate outreach at Goldman Sachs (GS). In August 2005, when she was in Washington, D.C. and working for Condoleezza Rice as Assistant Secretary of State for Cultural and Educational Affairs, she dreamed up this Mentoring Partnership. "I have an idea!" Dina exclaimed one afternoon when I paid her a casual visit at her State Department office. She suggested that we start a mentoring program together. Fortune, through its Most Powerful Women Summit, could recruit the mentors; the State Department could work with its embassies around the world to supply the mentees. I loved the idea. Ten minutes later, Under Secretary of State Karen Hughes walked into Dina's office. "Great idea," Karen said, after hearing our 60-second pitch. "Do it."

Talk about powerful women reaching out horizontally. The hard-core Republicans in the State Department quickly recruited an organization to help launch the Fortune/U.S. State Department Global Women Leaders Mentoring Partnership: Vital Voices, chaired by Melanne Verveer, who was Hillary Clinton's chief of staff when she was First Lady. Vital Voices is a renowned not-for-profit that empowers women throughout the developing world.

The grand mission of this Mentoring Partnership is to do just that: empower more than just the 35 stars who spent the month of May in America. These mentees have returned home and are now creating their own programs, such as mentoring and microfinance, throughout the developing world. As Rashmi Tawari, an alum of the program in India, says, "I feel empowered, so now I can empower other women."

Pattie