1954, The Manichaean hymn-cycles in Parthian (London Oriental Series, Vol. 3). London: Oxford University Press.
1975, A History of Zoroastrianism, Vol. 1 (Handbuch der Orientalistik Series). Leiden: Brill; Repr. 1996 as A History of Zoroastrianism: Vol 1, The Early Period.
1977, Zoroastrianism: The rediscovery of missing chapters in man's religious history (Teaching aids for the study of Inner Asia). Asian Studies Research Institute: Indiana University Press.
1977, A Persian Stronghold of Zoroastrianism. London: Oxford University Press; Repr. 2001
1978, A Reader in Manichaean Middle Persian and Parthian (Acta Iranica Monograph Series). Leiden: Brill.
1979, Zoroastrians: Their Religious Beliefs and Practices (Library of religious beliefs and practices). London:Routledge/Kegan Paul; Corrected repr. 1984; repr. with new foreword 2001.
1982, A History of Zoroastrianism, Vol. 2 (Handbuch der Orientalistik Series). Leiden: Brill. Repr. 1996 as "A History of Zoroastrianism: Vol 2, Under the Achaemenians".
1984, Textual Sources for the Study of Zoroastrianism (Textual Sources for the Study of Religion). London:Rowman & Littlefield.
Repr. 1990
1987, Zoroastrianism: A Shadowy but Powerful Presence in the Judaeo-Christian World. Friends of Dr. Williams: London.
1988, "The religion of Cyrus the Great", in A. Kuhrt and H. Sancisi-Weerdenburg Achaemenid History III: Method and Theory, Leiden: Brill.
1991, A History of Zoroastrianism: Vol. 3, Zoroastrianism Under Macedonian and Roman Rule (Handbuch der Orientalistik Series). With Frantz Grenet, Leiden: Brill.
1992, Zoroastrianism: Its Antiquity and Constant Vigour (Columbia Lectures on Iranian Studies, No 7). Cosa Mesa: Mazda.
Utkommer inom kort: A History of Zoroastrianism: Vols 5-7, under the editorship of Albert de Jong.