Shefer attended a Russian School in Chisinäu before making aliyah to Ottoman-controlled Palestine in 1913. He joined the Tzeiri Zion youth group, and later became a member of Hapoel Hatzair. After David Ben-Gurion and Yitzhak Ben-Zvi were expelled by the Ottoman authorities, he was a member of the Pole Halvri central committee. In 1917, he volunteered to join the Jewish Legion. After be- ing demobilised he lived in the Lower Galilee. In 1919, he was amongst the founders of Ahdut HaAvoda, and the following year helped establish kibbutz Ayelet HaShahar. He worked as a member of the mounted platoon of the special police that guarded the villages in the area. In 1921 he was also amongst the founders of the Histadrut. Shefer moved to Tel Aviv, where he became secretary of the Tel Aviv Workers Council, and a member of the city council in 1929. In 1939, he became secretary of Mapai. Between 1939 and 1945 he served in the British Army during World War I. Upon his return to Palestine after the war, he became a member of theHaganah's na- tional command, and also served as acting head of national staff. In 1949, he became a member of the HaKibbutz HaMeuhad secretariat. wTo years later he was elected to the Knesset on the Mapai list, and was appointed Depuyt Speaker. When HaKibbutz HaMeuhad split in 1952, he was amongst the founders of the Mapai-aligned Ihud HaKvutzot VeHaKibbutzim.