R. Abraham Isaac ha-Kohen Kook, first Ashkenazi chief rabbi of modern Erez Israel. Rav Kook was born in Griva, Latvia in 1865. His father was a student of the Volozhin Yeshiva, the center of mitnagdut, whereas his maternal grandfather was a member of the Hassidic movement. He entered the Volozhin Yeshiva in 1884, where he became close to the Rosh HaYeshiva, Rav Naftali Zvi Yehuda Berlin (the Netziv). Already in his youth, he was well known as a prodigy. At the age of 23, he entered his first rabbinical position. Between 1901 and 1904 he published three articles which anticipate the fully developed philosophy which he developed in the Land of Israel. In 1904, he came to the Land of Israel to assume the rabbinical post in Jaffa, which also included responsibility for the new secular Zionist agricultural settlements nearby. His influence on people in different walks of life was already noticeable, as he attempted to introduce Torah and Halakha into the life of the city and the settlements. The outbreak of the First World War caught him in Europe, and he was forced to remain in London and Switzerland for the remainder of the war. While there, he was involved in the activities which led to the Balfour Declaration. Upon returning, he was appointed the Rav of Jerusalem, and soon after, as first Chief Rabbi of Israel (though the state had not yet been been born). Rav Kook was a man of Halakha in the strictest sense, while at the same time possessing an unusual openness to new ideas. This drew many religious and nonreligious people to him, but also led to widespread misunderstanding of his ideas. He wrote prolifically on both Halakha and Jewish Thought, and his books and personality continued to influence many even after his death in Jerusalem in 1935. His authority and influence continue to this day. R. Kook was a prolific writer, who, according to his students, wrote out of the constant urge to create. He never attempted to construct a comprehensive system, and his style mirrors the quality of his personal insights and mystical reflections.

R. Ya'acov Moshe Charlap, (1883–1951), Erez Israel rabbi, was born in Jerusalem, where his father, who had immigrated from Poland, was a dayyan in the bet din of R. Moses Joshua Judah Leib Diskin. His main teacher was the Jerusalem scholar, R. Zevi Michael Shapira and under his influence R. Charlap engaged in Kabbalah and practiced asceticism. After R. Shapira's death, he published Zevi la-Zaddik (1907), in his memory, and arranged his writings for publication, publishing his halakhic work Ziz ha-Kodesh (two parts, 1920–1951) with his own additions. When R. A. I. Kook arrived in Erez Israel in 1904, R. Charlap immediately came under his influence, and a bond of unusual intimacy developed between them which was strengthened by their common interest in Kabbalah and their leaning toward mysticism and poetic meditation. R. Charlap was particularly attracted by R. Kook's thought which stressed the special role of the Jewish people as a whole, the sanctity of the land of Israel, and the Zionist movement and its upbuilding of Erez Israel—a first stage in the future messianic redemption. When in 1908 the Sha'arei Hesed district of Jerusalem was established outside the Old City, he was appointed its rabbi. In 1912 he was appointed to the Ez Hayyim yeshivah. In 1918 he was one of the chief speakers at the meeting of the rabbis of Jerusalem with Chaim Weizmann demanding that the Zionist movement confine itself to the political field, but he refused Weizmann's offer that he undertake the conduct of religious affairs in the yishuv. When the Merkaz ha-Rav yeshivah was founded in Jerusalem by Kook, R. Charlap was invited to serve as head of the yeshivah and he continued in this post until his death. After the death of R. Kook in 1935, many expected R. Charlap to be chosen as chief rabbi, and in any case he was later regarded by many as his natural successor. R. Charlap never left Erez Israel during his life and regarded it as a merit "that I never departed from holy confines and never [breathed] the air [or trod the] ground of the land of the gentiles."