In the pantheon of modern Jewish leaders, Chaim Weizmann is a giant. One of the founding fathers of the state of Israel and its first president, he was also a president of the World Zionist Organization and a chemist of the first rank, for whom Israel's renowned Weizmann Institute of Science was named. Yet there has never been a scholarly biography of Weizmann. His own autobiography, <em>Trial and Error</em>, written largely from memory, is riddled with errors. Here at last is a book by an authority on the history of Zionism that fills the gaps in our knowledge. A biography of Weizmann is in many ways a history of the Jewish people in the modern period. This book delves into the factors that shaped Weizmann's personality and world view. It analyzes his relations with his family and other men and women, among them the major Jewish personalities of his day. In the process it deals with the tensions between Zionists and anti-Zionists, the impact of Zionism on the Eastern and Western Jewish communities, and the role of British, French, and German governments during various phases of the movement to establish a Jewish homeland. The book also pays much attention to Weizmann's scientific work. This volume ends with Weizmann at the age of 40 on the eve of World War I, when he was thrust into the center stage of world politics as a major negotiator for the Balfour Declaration. A subsequent volume will cover the remainder of his life. <em>About the Author</em>: Jehuda Reinharz is Richard Koret Professor of Modern Jewish History and Director of the Tauber Institute for the Study of European Jewry at Brandies University. He is author of <em>Fatherland or Promised Land: The Dilemma of the German Jew, 1893-1914</em> and the editor of <em>The Letters and Papers of Chaim</em> <em>Weizmann, 1918-1920</em>