Kaplan's major influence was Rabbi Zvi Aryeh Rosenfeld (1922–1978), who single-handedly introduced the teachings of Rebbe Nachman of Breslov to American shores beginning in the 1950s, inspiring many students at Brooklyn yeshivas, especially Torah Vodaas. Working together, Kaplan and Rosenfeld translated and annotated "Rabbi Nachman's Tikkun" (based on the "Tikkun HaKlali"). At Rosenfeld's suggestion, Kaplan also produced the first-ever English translation of "Sichot HaRan" ("Rabbi Nachman's Wisdom"), which Rosenfeld edited. He also translated and annotated "Until the Mashiach: The Life of Rabbi Nachman", a day-to-day account of Rebbe Nachman's life, for the newly established Breslov Research Institute founded by Rosenfeld's son-in-law, Chaim Kramer. Kaplan's later writings further explored Hasidut, Kabbalah and Jewish meditation. (Kaplan himself utilized the meditative form of Kabbalah on a daily basis.) Kaplan wrote three well-known books on Jewish meditation. These books seek to revive and reconstruct ancient Jewish practices and vocabulary relating to meditation. He also wrote and translated several works related to Hasidic Judaism in general, and to the teachings of Rabbi Nachman of Breslov in particular.