Oppenheimer's sociology is developmental in character, combining in an independent way elements from the theories of Marx, Spencer, Gumplowicz, and also from the instinct theory of McDougall; to these is added a melioristic intention. Oppenheimer considered accumulation of wealth and power, and hence gross inequality among men, as originating from social conflict, exemplified in earliest times chiefly by the subjugation of peaceful farmers, craftsmen, and traders by conquering nomads and pirates. The "economic means" of accumulation through one's own work is thereby replaced by "political means," i.e., force of arms, starting with payment of tribute, then leading to serfdom, feudalism, and finally to the development of antagonistic classes under capitalism. The central evil is the monopolization of land, which forces rural populations into urban areas, and creates what Marx had defined as the "industrial reserve army." Consequently, if the monopolization of land were replaced by an agrarian cooperative system of independent farmers, free competition could be restored and a "liberal socialism" established. Oppenheimer's belief that the removal of evil institutions would do away with the domination of man by man and lead to social harmony has a dogmatic ring.

Oppenheimer's interest in Zionism dated from 1902, when Oskar Marmorek and Johann Kremenetzky introduced him to Theodor Herzl. Herzl asked Oppenheimer to elaborate the economic and agricultural parts of the Zionist program, which he did in 1903 at the Sixth Zionist Congress in Basle. In 1911 the Palestine Office of the Zionist Organization in Jaffa established at Merhavyah a cooperative settlement based on Oppenheimer's ideas. Although it did not prove successful and had to be reorganized, the Merhavyah experiment laid the foundation for cooperative agricultural settlement in Erez Israel.

As an opponent of nationalism, Oppenheimer became alienated from the Zionist movement, and in 1913 he withdrew from any official participation. Nevertheless, he maintained his interest in the development of Erez Israel and in Jewish social problems. During World War I he became aware of the misery of the Jewish population in Eastern Europe. In 1934–35 Oppenheimer visited Palestine and explained his concepts to Jewish labor leaders, but his ideas were not enthusiatically received. His most important works are Der Staat (1907; The State, 1914) and System der Soziologie (4 vols., 1922–35). Some of his articles on the Merhavyah experiment were included in the books Genossenschaftliche Kolonisation in Palaestina (1915); Merchavia (1914); and Wege zur Gemeinschaft (1924). He also published an autobiography, Erlebtes, Erstrebtes, Erreichtes (1913). G. Kressel's Franz Oppenheimer (Hebr., 1972) contains hitherto unknown information about how Oppenheimer inspired Herzl to work for Jewish settlement in Erez Israel.

Akiva Jacob Ettinger was an agricultural expert and founder and administrator of Jewish settlements in Erez Israel. He came from a distinguished family (his mother was descended from R. Akiva Eger). He studied agriculture at the University of St. Petersburg and in West European countries.

Representing the Jewish Colonization Association (ICA), he took part in 1898 in an investigation of the situation of Jewish farmers in southern Russia, and was then asked to establish a Jewish model farm in Bessarabia. In 1911 he served as agricultural adviser to ICA in South America. Ettinger was sent to Erez Israel in 1902 by the Odessa Committee of Hovevei Zion to investigate the state of the Jewish settlements. In 1914 he was asked by the Zionist Organization and the Jewish National Fund to serve as adviser and inspector for Jewish agricultural settlement in Erez Israel, but because of the outbreak of war he went to The Hague, where the Jewish National Fund had its temporary head office. There he wrote a programmatic booklet, Jewish Colonization in Palestine: Methods, Plans and Capital .

During the negotiations over the Balfour Declaration, Ettinger was invited by Chaim Weizmann to London as adviser on settlement matters, and composed a comprehensive memorandum, Palestine after the War: Proposals for Administration and Development (1918). Ettinger settled in Palestine in 1918, serving as director of the agricultural settlement department of the Zionist Organization until 1924. In 1919, after the purchase of land for Kiryat Anavim on the rocky Judean hills, he founded the village which became a model for hill settlements. His most important achievement involved the vast settlement project of the Jezreel Valley during 1921–24. From 1924 to 1932 Ettinger played a prominent role on behalf of the Jewish National Fund in the purchase of land and the drafting and implementation of settlement (the kevuzah, kibbutz, and moshav) and aided their development on a mixed farming basis with emphasis on dairy farming and orchards. He also introduced new afforestation methods. From 1932 until his death Ettinger was adviser to the agricultural Yakhin Company of the Histadrut. Ettinger wrote many articles on agriculture in Erez Israel. His booklets include Nahalal (1924), Emek Yizre'el (1926), and Ha-Karmel (1931). His memoirs are titled Im Hakla'im Yehudim ba-Tefuzot (“With Jewish Farmers in the Diaspora,” 1942), and Im Hakla'im Ivriyyim be-Arzenu (“With Hebrew Farmers in our Country,” 1945).