One hundred years ago today, 50 activists meeting in New York established Young Judaea, which became America's largest Zionist youth movement. The movement's centennial occurs in rough times. Hadassah, its generous sponsor since 1967, is cutting back. Membership is down. Many consider youth movements outmoded in the Internet era, and Zionism itself passÃ©. Nevertheless, Young Judaea's glorious history illustrates why the movement must not die. We need Young Judaea to thrive as an altruism incubator, a community builder, an identity enhancer, providing an inspiring model of 24-7 Judaism while molding a Zionist response to today's challenges. I first entered the "Z-House," Zionist House, Young Judaea's Queens regional headquarters in 1975. I was a very serious, very square 14-year-old, sporting Poindexter glasses, dragging a big black briefcase as a schoolbag. Young Judaea liberated me from being so conventional and conformist. Unlike many movement friends, I liked my parents, my synagogue, my Jewish day school education. Still, the movement added edge, zest, passion, wrapped up with many of the best friendships I would ever make - and still enjoy. AS REGIONAL LEADERS and through the movement's senior camp, Tel Yehudah, my friends and I joined a nationwide network of people who cared about Israel, Judaism, and the world. We believed ideas counted. We believed Arik Einstein's song "you and I will change the world." We debated issues constantly, from the morality of playing American rock music or using blow dryers in a Zionist camp to the compatibility of a Jewish state with universal values. We were blessed with extraordinary madrihim, leaders, who took our ideas seriously while making education and activism fun. To single out some risks slighting many. Still, I appreciate how my witty, wry, delightfully-tortured, super-smart club leader Greg Musnikow; my reedy, exuberant, deeply intellectual and compellingly spiritual camp unit head, Steve Copeland; and the gruff, charismatic, hard-hitting, fast-talking, substantive but endlessly entertaining pied piper of Tel Yehudah, Mel Reisfield, each shaped me as a thinker, an educator, a Jew, a Zionist, an historian, a human being, a friend, even a parent decades before I married. The movement gave us a community, what we call today a platform, for learning, leadership, identity-building, social-activism, maturing experiences and fun. I still quote insights I learned at camp about the clash between tradition and modernity in the 1800s that created Zionism and shaped today's world. I remember the first time I took 40 campers hiking, suddenly realizing I was in charge and personally responsible for their safety. AS JUDAEANS, we translated our formal and informal Jewish learning into vital modes of Jewish living, rooted in our history and traditions, influenced by Western values and sensibilities, enlivened by song and dance, perpetual laughter and occasional tears. We fought to free Soviet and Ethiopian Jews, to defend Israel and save the environment, to help kids with special needs and remember the needy, all through the movement. Amid this serious work, we bonded. We questioned and quarreled, paired off and broke up, giggled and pranked. We lived large. These experiences taught us that Zionism was more than pro-Israelism, that Zionism was not just the Jewish national liberation movement reestablishing our homeland but was a vehicle of individual liberation fulfilling big dreams, personally and collectively, Jewishly and universally. Our Zionism was subversive. It began by critiquing American Jewry and modernity, repudiating the materialism, vulgarity, emptiness and ignorance warping so many Jewish - and American - institutions. We examined the Jewish community, American life, Israel itself, as they were - and said, "We expect more, we demand more": more justice, more ethics, more intimacy, more safety, more dynamism. As general, nonpartisan, pluralistic Zionists, we valued klal Yisrael, the unity of the Jewish people, over the partisan rivalries plaguing the Jewish world and Israel. Most Judaeans were liberal and nonobservant. Nevertheless, we observed Shabbat publicly, served kosher food exclusively and prayed daily. This openness enabled religious and nonreligious Jews, liberals and conservatives, to talk together and, of course, argue together. ALTHOUGH THE MOVEMENT did not save the world (yet), it produced extraordinary alumni. So many movement graduates went into helping-professions, communal leadership, intellectual pursuits, that if ex-Judaeans established a church, it would be called "Our Lady of the Social Workers and the Educators, the Community Leaders and Philanthropists." I could boast about my superstar friends in America and Israel, describing their impact on campus and in communities, in the music business and the coffee business, in virtually creating the Israeli environmental movement while keeping the Zionist flame burning in both countries. I could boast about how the movement kibbutz, Ketura, unites religious and secular Israelis, keeping kibbutz ideals alive today, thriving as a community based on altruism not selfishness. But my Judaean friends' greatest collective accomplishment is the honorable, ethical lives they lead, their rich Jewish family lives, the noble values they fulfill daily. A recent Hadassah survey showed - surprise, surprise - that movement alumni were much more likely to marry Jewish, light Shabbat candles, contribute to community, move to Israel. I can add that my Judaean friends are much less likely than others to divorce, neglect their children, indulge in pathological drug and alcohol use, forget their obligations to others, even as many personally prosper. With Israel established and thriving, Soviet and Ethiopian Jews freed, American Jews feeling thoroughly at home, many pronounce Zionism irrelevant. But Israel still needs defending and perfecting, and American Jews desperately need education and inspiration. Young Judaea's constructively communal countercultural sensibility, its vision of Zionism as a moral system and source of hope, is needed now. The Birthright Israel identity-building revolution through Israel experiences of the last decade reflects a Judaean sensibility applied on a mass scale. Young Judaea never was and never will be a mass movement. But the movement could nurture a committed cadre of this next generation's Zionist dreamers and doers - as it has been doing for the last hundred years. The writer is professor of history at McGill University and the author of Why I Am a Zionist: Israel, Jewish Identity and the Challenges of Today and Leading from the Center: Why Moderates Make the Best Presidents. He divides his time between Montreal and Jerusalem.