Prof. Sacha Stern specializes in ancient and medieval Jewish history, with a special interest in time, calendars, and chronology. He has also researched and published articles on early rabbinic attitudes to pagans and paganism, and more generally on early rabbinic literature and history.

His latest monograph, Calendars in Antiquity (2012), examines the calendars of ancient Mesopotamia, Egypt, Persia, Greece, Rome, Gaul, and other parts of the Mediterranean and the Near East, from the origins until the Jewish and Christian calendars of late Antiquity. He highlights the political context in which ancient calendars were designed and managed. Most ancient calendars were set and controlled by political rulers. They served as expressions of political power, as mechanisms of social control, and sometimes as assertions of political independence, or even of sub-culture and dissidence. Stern contends that calendars and the way they are reckoned should not be treated as a technical curiosity, but rather as an integral part of ancient culture and society.

Since 2008, he has been directing several major research projects on the Jewish calendar in the Middle Ages: "Medieval Monographs on the Jewish Calendar" (AHRC), "The Jewish Calendar in Early Islamic Sources" (Leverhulme), "Medieval Christian And Jewish Calendar Texts From England And Franco-Germany" (Leverhulme), and "Jewish calendar controversies in the 10th-11th centuries Near East: a historical and codicological analysis" (British Academy), with a total staff of five research associates and several international collaborators.

In 2013-18, he was Principal Investigator of an ERC (European Research Council) Advanced Grant research project entitled Calendars in Late Antiquity and the Middle Ages: standardization and fixation. Together with five research associates, he studied the evolution of calendars in late antique and medieval societies by focusing on several research areas: the seven-day week in the Roman Empire, late Roman calendar conversion tables (the hemerologia), and medieval monographs in Arabic and Hebrew on astronomy and the many ancient and medieval calendars (http://www.ucl.ac.uk/hebrew-jewish/research/research-pro/calendars-antiquity-middle-ages). In collaboration with Marina Rustow (Princeton), he has written a monograph on The Jewish Calendar Controversy of 921/2, incorporating a new edition of a large corpus of Cairo Genizah sources (forthcoming).

In 2018, he led an international research team with Jonathan Ben-Dov (Haifa University) at the Israel Institute of Advanced Studies on 'The Day Unit in Antiquity and the Middle Ages'.

From September 2018, he is Principal Investigator jointly with Ronny Vollandt (LMU, Munich) of a Fritz Thyssen research project on "Qaraite and Rabbanite Calendars", with Nadia Vidro as Research Associate.

Sacha Stern is editor of the Journal of Jewish Studies (jointly with Alison Salvesen, Oxford University) and of the Brill series Texts and Studies on Time, Astronomy, and Calendars (jointly with Charles Burnett, the Warburg Institute).