The IOP also sponsors and participates in a wide range of conferences and colloquiums that encourage exchange among scholars of different countries.
Some of the international public lectures where IOP-sponsored scholars participated in are:
- University of Constance: "Religion and the Structure of Modern Western Society," Thomas Luckmann
- Oxford University: "New Religious Movements: Challenge and Response," Bryan Wilson
- University of Paris: "Religiosity in Daily Life," Michel Maffesoli
In November 1991, a lecture on "Gandhism and the SGI Movement" was delivered by Dr. N. Radhakrishnan, Director, Gandhi Smriti and Darshan Samiti, New Delhi.
In 1997, a public lecture series was held on the theme "Our Aging Society and what it means to us." The subthemes and the speakers were as follows:
- "Buddhism and Birth, Old Age, Sickness and Death," Mitsuyoshi Saigusa, Professor Emeritus, Tsukuba University
- "Welfare and the Aging Society," Katsuhiko Fukushima, Professor, Soka University
- "Bioethics in Old Age," Kazumasa Hoshino, Professor Emeritus, Kyoto University and Former Chairman of the Japan Association for Bioethics.
- "Healthy Aging for Longer Life," Kiyokazu Noda, Professor Emeritus, Kanagawa Dental College, Chairman of the Japan Health Medicine Association.
The following public lecture series on the Lotus Sutra was held in 1998:
- "The Boddhisatva Spirit Expounded in the Lotus Sutra," Dr. M. I., Vorobyova Desyatovskaya, Manuscipt Department Supervisor at the Institute of Oriental Philosophy, Russian Academy of Sciences, St. Petersburg.
- "The Lotus Sutra and the Xixia Kingdom," Evgenij I. Kychanov, Director, Institute of Oriental Philosophy, Russian Academy of Sciences, St. Petersburg.
- "Toward the 21st Century, the light of the Lotus Sutra," Dr. Lokesh Chandra, Director of the International Academy of Indian Culture
The following public lecture series on Buddhism was held in 1999:
- "Budhism in Easter Asia," Kiyotaka Kimura, Professor, Tokyo University
- "Buddhism in Japan," Fumihiko Sueki, Professor, Tokyo University
- "Buddhism in Korea," Kim Jong Whan, Professor, Pusan University
- "Buddhism in Taiwan," Akikazu Minowa, Assistant Professor, Aichi Gakuin University
- "Buddhism in China," Hiroshi Sugano, Professor, Soka University
In November and December 2001, the IOP hosted a public lecture series on "Century of Women and Religion," exploring current involvement of women in religion. Leading religious scholars and experts gave their insights:
- "Hinduism and Women--Image of Mothers in Hinduism," Sandip K. Tagore (Professor of Letters, Otemon University, Osaka; Director of Tagore-Einstein Council, Japan Branch)
- Under Armed Conflict--The Women of Islam and Us," Mari Oka (Assistant Professor of Integrated Human Studies, Kyoto University, Kyoto)
- "Women in Christianity--from Fundamentalism to Feminist Theology," Katsuhiro Kohara (Assistant Professor of Theology, Doshisha University, Kyoto)
- "Women's Issues in Buddhist History," Yoshie Kurihara (Staff Researcher, Institute of Oriental Philosophy)