Angela Merkel

For the second year in a row, Angela Merkel, the first woman to become chancellor of Germany, ranks No. 1 on our list of the World's 100 Most Powerful Women. She continued to impress the world with her cool leadership at two back-to-back summits. First, she stuck to her principles, getting G-8 leaders to agree to significant cuts in carbon emissions, among other things. Merkel later corralled European Union countries into an agreement on a treaty to replace the E.U. constitution.
Meanwhile, China's vice premier, Wu Yi (No. 2), continues to help lead a government that oversees an economy whose gross domestic product may soon eclipse Germany's, making it the third-biggest economy in the world. Wu recently stared down U.S. Treasury Secretary Henry Paulson when he made myriad demands, including a revaluation of the yuan, in recent strategic economic talks with the U.S.
But China faces enormous challenges in improving its rickety social, legal and economic infrastructure, which now has to contend with an overheated stock market, unsafe and shoddy products and severe pollution.