As part of a broader turn in humanities scholarship toward emotion since the late 20th century, scholars of religion increasingly have explored how emotion has been a key component in the lives of religious Americans. The relation of emotion to religious ideas has been particularly important in this nascent scholarship. In exploring how emotions and religious ideas are intertwined, scholars have focused on emotions such as love, melancholy, fear, and anger, among others. However, for reasons having to do with the historiography of American religion, as well as with categories that have governed much academic study of religion in America, the feeling of emptiness, which is so crucial to understanding Buddhism, and other Asian religions, has been underestimated for its role in American religions. In America, the feeling of emptiness plays a central role in religious practice, community formation, and identity construction, among Christians (the religious majority) but also in other religious communities. This essay describes some of the ways in which the feeling of emptiness has been expressed in American religions, and in American culture more generally, comments on how it has been joined to certain ideas at various times, and suggests how it has played a central role in shaping relations between religious groups in a society where religion is disestablished. The approach here is eclectic, blending historical narrative with cultural analysis, and the essay proceeds thematically rather than chronologically. Focusing on the feeling of emptiness allows a fresh perspective on religious practice in America, prompts new questions about belief and community, and enables new lines of interpretation for the development of religious ideas in America. Christians, Buddhists, Jews, and other religious communities in America have distinct ways in which they interpret the feeling of emptiness as a spiritual phenomenon. Religious persons often conceptualize it as an emotional experience of great value. Among Christians, it is important as a sign of an emptying of the self of immorality, distractions, and worldly clutter in preparation for being filled with the grace of God. Accordingly, Christians and others in America have developed spiritual disciplines aimed at cultivating the feeling of emptiness and advancing it to a point where deep longing becomes deep fulfillment. Religious practices involving the body include fasting, which is emptying the body of food, and tears, which empty the body of fluids. Bloodletting is also a notable practice, and, for those who do not cut or otherwise make bloody sacrifice (including war and lynching), bloodletting nevertheless is revered as a model discipline of emptying. There are aspects of sexual practices and the performance of work that also are exercises in self-emptying. All such disciplines are expected to prompt and enrich the feeling of emptiness. The severe fast, the deep feeling of emptiness, the desperate longing, the distancing from God becomes, paradoxically, a drawing closer to God. From the earliest settlement of North America, white Europeans and their descendants constructed the emptiness of the land to match the emptiness of their souls. Americans claimed to feel space. They expressed the spiritual feeling of emptiness in ideas about North America as a barren desert, crying to be filled by colonists and their descendants. The Great American Desert, a fiction created in the early 19th century, was one way in which Americans continued to imagine space as empty and themselves, as God’s exceptional nation, as the agents of fullness. American fascination with millennialism was a valorization of the fullness of eternity over the emptiness of history. Millennial movements and communities in America felt time as they did space, and when American Christians felt historical time they felt its emptiness. Americans have constructed elaborate and richly detailed depictions of the end as they look forward to a time when empty time will become eternity, fullness. Christian groups in America, populated by persons who cultivate emptiness, have defined themselves largely by saying what they are not. Both persons and communities, invested in the feeling of emptiness, mark personal and collective boundaries not by projecting into the social world a pristine essence of doctrine so much as by pushing off from other groups. Committed to emptiness, there is little to project, so the construction of identity takes place as an identification of Others. Such a process sometimes leads to the demonization of others and the production of identity through the inventorying of enemies.