This dissertation examines the origins and development of a key religious orientation in contemporary Islamic thought. At the beginning of the twentieth century, the term "Salafiyya" was linked to a transnational movement of Islamic reform whose proponents strove to reconcile their faith with the Enlightenment and modernity. Muhammad Abduh and Rashid Rida were among its foremost representatives. Toward the end of the twentieth century, however, the Salafi movement became inexplicably antithetical to Islamic modernism. Its epicenter moved closer to Saudi Arabia and the term Salafiyya became virtually synonymous with Wahhabism.

The evolution of the Salafiyya and its apparent turn from modernism to purism, within less than a century, is a phenomenon that remains shrouded in mystery and marked by contradiction. To this day, it causes recurrent problems among scholars in various disciplines who try to understand the genealogy of the movement. Is there really a common lineage between the two types of Salafiyya? This dissertation answers in the affirmative and endeavors to demonstrate how the meaning and substance of this religious orientation changed so drastically.

The life and thought of Taqi al-Din al-Hilali (1894-1987), a Moroccan Salafi and globetrotter who lived through the various stages of the evolution of the Salafiyya, serves as a case study. Because of his contacts with the most prominent Salafi figures of the twentieth century, both modernist and puristic, al-Hilali provides us with an unprecedented opportunity to shed light on the connections between these actors. By putting his experiences in context and showing how the changes in his religious ethos corresponded to larger trends, this dissertation argues that the rise of a transnational and generic Islamic consciousness, especially after the First World War, facilitated the growth of religious purism within key Salafi circles. The Salafis who most emphasized religious unity and conformism across boundaries usually developed puristic inclinations that proved useful in the second half of the twentieth century. Due in part to their affinities with the Saudi religious establishment, they survived the postcolonial transition and kept thriving while the modernist Salafis eventually disappeared.