In 1974, she earned her Doctor of Philosophy (PhD) degree at the School of Oriental and African Studies, University of London with a thesis titled "The Mawali in the Umayyad period".

[citation needed] She was accepted as an occasional student at King's College London and followed a course in medieval European history, especially church-state relations.

[10] Though she began as a scholar of broader military and economic history of the Near and Middle East, Crone's later career focused mainly on "the Qur'an and the cultural and religious traditions of Iraq, Iran, and the formerly Iranian part of Central Asia".

[11] In their book Hagarism (1977), Crone and her associate Michael Cook, both then working at the School of Oriental and African Studies in London, provided a new analysis of early Islamic history.

[12] Fred M. Donner viewed the book as a "wake-up call": despite initial repudiation, it set a milestone by pointing out that scholars need to "consider a much more varied body of source material than most were used to using, or trained to use".

[14] Michael G. Morony remarked that "Despite a useful bibliography, this is a thin piece of Kulturgeschichte full of glib generalisations, facile assumptions, and tiresome jargon.

She also suggested that while Muhammad never traveled much beyond the Hijaz, internal evidence in the Qur'an, such as its description of his opponents as "olive growers", might indicate that the events surrounding Muhammed took place nearer the Mediterranean than in Mecca.