Meir Yaari (1897-1987) was the leader of Hashomer Hatza'ir, a movement which took an active part in shaping the history of the Jewish people in the crucial decades of the twentieth century. Its Kibbutzim had a leading role in matters of aliyah, settlement, and defense in mandatory Palestine and then independent Israel, and its members were among the organizers of Jewish resistance and revolt during the Holocaust. This biography discusses pivotal issues in the history of the Jewish people and the State of Israel, such as the friction between Zionism and socialism, the Arab question, the absorption of new immigrants, and generation gaps and conflicts. The book blends individual and collective perspectives and never loses sight of the tension between ideology and reality.