(1897-1987)
Born in Rzeszow, Galicia, he studied agriculture, served in the Austrian army during World War I, and was the leader of Hashomer Hatzair in Vienna before immigrating (see ALIYA) to Palestine in 1919. Ya'ari was the first secretary of Hashomer Hatzair in Palestine. He was a founder of Kibbutz Mer-havya and became the first secretary of Kibbutz Artzi (the kibbutz movement of Hashomer Hatzair) in 1927. Combining Marxism and some of Ber Borochov's central ideas, he crystallized the doctrine of Hashomer Hatzair—a synthesis between Zionism and socialism. While representing Hashomer Hatzair, Ya'ari was one of the founders of the Histadrut in 1920. Hashomer Hatzair also created its own party, headed by Ya'ari, whose efforts to expand met with success in January 1948, when Hashomer Hatzair and Ahdut Haavoda Poale Zion merged to form Mapam (United Workers' Party), which was intended to provide a left-wing, Marxist-Leninist alternative to Mapai.
In the early 1950s, Ya'ari became disenchanted with the Union of Soviet Socialist Republics and (with Ya'acov Hazan) fought a vigorous rear-guard action within Hashomer Hatzair and Mapam against those elements who remained loyal to Moscow and who ultimately found a political home in the Israel Communist Party. After the 1954 split in Mapam, Ya'ari consolidated control and led the majority in the party, returning to the framework of a small left-wing Zionist party. This party participated in Israel's governments from 1955, even though it was opposed to some political decisions, such as the 1956 Sinai Campaign. Together with Ahdut Haavoda and Mapai, it founded the Alignment (Maarach) in 1968, with Ya'ari serving as a Knesset member until 1973, when he resigned from the Knesset and from his office of party secretary. He died on 21 February 1987 at Kibbutz Merhavya.
Historical Dictionary of Israel. Bernard Reich David H. Goldberg. Edited by Jon Woronoff..