Secularization is a major theoretical concept with its own paradigm in different scholarly fields, including the study of religion. While there are several uses and definitions of the term, it has generally referred to a cultural process in which religious institutions lose authority and religion has declining relevance for the individual. Conceptually, “secular” has been viewed as the opposite of “religious,” and “secularism” as an ideology expressing the idea of separating state from religion. Scholars of religious studies (and scholars of Buddhism) have begun challenging this binary, suggesting processes of secularization to also reinforce the importance of the “religious” within society and culture so that religion is revitalized. Others have underlined the necessity of using the concept as relevant tool in the comparative study of religion. Secularization is typically used as an explanatory concept related to the modernization processes of the 18th–19th centuries, which was a period characterized by Enlightenment thinkers, rationality ideals, functional differentiation, and/or general disenchantment of the world. But the concept also reflects postmodern and global transformations in recent decades, which have had further effects on the continuing decrease of religious authority in some regions. Some of the elements of secularization can be traced much further back in history. Critical reflections on religious assertions, the humanization of cosmologies, and the desacralization of the world were known in early Axial religions, not least Buddhism. As a religion questioning its own epistemological assumptions, Buddhism did not, however, relativize its own institutional importance, but rather established the sangha as a religious organization balancing between monastic religiosity and criticism of (traditional) religion. The reform Buddhism of the 19th century also had elements of proto-secular Buddhism, formulated by important Buddhist figures such as Anagarika Dharmapala (b. 1864–d. 1933), Taixu (b. 1890–d. 1947) and D. T. Suzuki (b. 1870–d. 1966). Spokesmen of this “modern Buddhism” claimed that the religion was convergent with natural physics, Darwinian evolution, humanism, and individualism, seeing modernity as an inspiration for renewal and reformation. Interpretations of Buddhist ideas and practices in the light of modern ideals beyond traditional religious worldviews have been further developed in the transformation of these ideas and practices to Western settings. What has sometimes been called “secular Buddhism” is one such phenomenon, deconstructing what is seen as traditional or cultural elements while at the same time contributing new ideas and practices. Another kind of state-sanctioned and forced secularism can be seen in the policies of Communist China, where Buddhism (and all religion) was previously officially removed from society and in reality banned from the public sphere. In Japan, religious crises have forced Buddhist communities and organizations to rethink their own role in an increasingly secular society. With negative demographic developments in Buddhist Asia, new generations of Buddhists will decline in numbers, and, combined with increased individualization and decreasing religious authority, Buddhism in Asia will probably continue to experience aspects of secularization, even though the Eurocentric connotations of the concept are not directly transferable, the religious and cultural patterns in Asia are diverse, and secularization is not necessarily an irreversible development.