Waskow was ordained a rabbi in 1995 by a transdenominational beth din (rabbinical court) made up of Rabbi Zalman Schachter-Shalomi, with Lubavitch Hasidic lineage; Rabbi Max Ticktin, ordained by the Jewish Theological Seminary (Conservative); Rabbi Laura Geller, ordained by the Hebrew Union College (Reform); and Dr. Judith Plaskow, a leading feminist theologian.
Perl had received his semicha (rabbinic ordination) from Yeshiva University's Rabbi Isaac Elchanan Theological Seminary, and had previously served as Assistant Rabbi at Congregation Ahavath Torah in Englewood, New Jersey.
Many of the Yeshivot Hesder also support a Kollel and offer a Semicha ("rabbinic ordination") program, usually in preparation for the "Semicha of the Rabbanut"; many Hesder graduates also obtain semicha from Rabbi Zalman Nechemia Goldberg.
Returning to Lithuania to complete his studies, Unterman was ordained as a rabbi by Rabbi Refael Shapiro and opened his own yeshiva in the town of Vishnyeva around 1910.
He received four semichas: from Rabbi Serayah Deblitzky, a student of the Chazon Ish; Rabbi Ovadia Yosef, former Sephardi chief rabbi of Israel; Rabbi Betzalel Zolty, Ashkenazi chief rabbi of Jerusalem; and Rabbi Elazar Shach, a rosh yeshiva at the Ponevezh Yeshiva in Israel.
Gaining Semicha in 1902, he travelled to Germany where he became acquainted with a more modern form of Orthodox Judaism that had a more tolerant attitude to secular education and to political Zionism (although such attitudes were also present in the Lithuania of his youth, and in his grandfather).
He studied in the Łomża Kollel under the renowned Gaon Rabbi Aaron Yosef Bakst, and received semicha at the age of 23 from Rabbi Yitzchak Elchanan Spektor.
Among those who received semicha (Rabbinic ordination) from him were, the seventh Lubavitcher Rebbe, Rabbi Menachem Mendel Schneerson, Rabbi Mordecai Savitsky of Boston; Rabbi Zvi Olshwang (1873–1959?) of Chicago a brother-in-law of Rabbi Shimon Shkop; Rabbi Avrohom Elye Plotkin, the author of Birurei Halachot (a copy of the actual semicha is included in that work).