This essay provides an overview of demographic and organizational changes in American religion since 1965. We focus on religious beliefs and practices, congregational life, special purpose groups, religion outside of religious organizations, and transnational and global aspects of religion. American religious institutions are increasingly diverse, reflecting the growing ethnic, linguistic, and religious pluralism of the United States. Recent immigrants to the United States are more Catholic, more Orthodox, and less Christian than adult Americans overall, and they have joined existing congregations in addition to forming their own religious organizations. A substantial number of Americans now consider themselves spiritual, but not religious, and many do not identify with organized religion at all. American Christianity itself is more politically polarized than in the past, and individuals who are religiously active across traditions tend to be more politically and socially conservative than others with tensions evident around contemporary social issues such as abortion and homosexuality. Existing religious organizations and secular organizations such as hospitals, universities, and prisons have responded to demographic and religious changes by offering new or changed services and physical spaces to meet religious and spiritual needs. We encourage future scholars to address institutional changes in American religion by considering diverse people and traditions, asking questions about religion in religious and nonreligious organizations, and situating studies of the United States in their broader global contexts.