Professor Geo Widengren (1907–1996), holder of the chair in History of Religions and Psychology of Religions at Uppsala University between 1940 and 1973, is one of Sweden’s best-known scholars in the field of religious studies. His involvement in the start of the IAHR and publications on topics such as the phenomenology of religions, Iranian studies and Middle Eastern Religions make Widengren one of the founding fathers of the History of Religions as an academic discipline. This volume pays tribute to Widengren’s academic achievements and critically discusses his work in light of the latest academic findings and research.