Mori Yosef Kapach, son of Mori David Kapach, was born on 12 Kislev 5677 (1917) in Sana'a, Yemen. His grandfather, Mori Yihya Kapach, among the greatest of Yemen's sages of his day, was one of the founders of the Dor De'ah study group, known as the Darda'im, who sought to have the Yemenite Jewish community return to the Halakha that preceded the Shulchan Aruch, as ruled by Maimonides and Rabbi Sa'adia Gaon. They were opposed to the study of Kabbala and Zohar, and encouraged secular scholarship.
His grandfather's activities triggered resistance within the Jewish community. As a result, the local government became anxious about the regime's stability. The study group members were arrested and its activities outlawed, yet they continued to meet and study Torah. Mori David Kapach, his father, died when Mori Yosef Kapach was only a year old, having been arrested for studying Torah and beaten to death by policemen.
Mori Yoseph Kapach's mother died in 1922, when he was five years of age. He was raised by his aunt Sa'ada Vatchi and studied Torah with his grandfather, Mori Yihya Kapach. In 1931, his grandfather died, and Mori Yosef Kapach replaced him in his role teaching in the Beit Midrash. He continued to study with Mori Racha Tzarum, one of his grandfather's students.
In 1931, at the age of 16, Mori Yosef Kapach, too, was arrested by the authorities. Following his release, he married his young cousin, Bracha, and three years later their eldest son, David, was born.
Mori Yosef Kapach immigrated to Israel in 1943. He began his studies at the Mercaz HaRav yeshiva and continued towards his ordination as dayan at the Harry Fischel Institute. He was appointed as a dayan in the Jerusalem regional Rabbinic Court in 1950 and, some twenty years later, was appointed to the Great Rabbinic Court. Mori Yosef Kapach was a member of Israel's Chief Rabbinical Council and President of the Yemenite community in Jerusalem. He was awarded the Israel Prize for Torah Literature in 1969.
His principal religious work focused on translating and embellishing manuscripts by many of the early Sephardi sages, including Rabbi Sa'adia Gaon's Emunot VeDe'ot, Rabbi Yehuda HaLevy's Kuzari, Hovot HaLevavot by Rabbeinu Bahii Even Pekudah, Rabbi Natan's commentary on the Six Books of the Mishna, and numerous other works written in Judeo-Arabic. Maimonides' writings had a special place in his work: He translated Maimonides' Epistles, Guide to the Perplexed, Commentary on the Mishna, Sefer HaMitzvot, Treatise on Logic and edited a 24-volume annotated edition of the Mishne Torah. His numerous articles were gathered in three volumes, entitled "Writings".
Mori Yosef Kapach dealt extensively with the Jewish Yemenite heritage. His book, Halichot Teiman, describes the lifestyles of Yemenite Jewry. He edited the Shivat Zion tachlal (siddur) – an authentic Yemenite prayer book that follows Maimonides' method – and the Siah Yerushalem prayer book.
Mori Yosef Kapach passed away on the eve of 18 Tammuz 5760 (2000) and was buried on the Har HaMenuchot cemetery in Jerusalem.