This chapter examines one of the most visible institutional expressions of contemporary religious vitality, the American-style evangelical ‘megachurch’, which has proliferated globally since at least the 1970s—with the notable exception of the European continent. While it is tempting to attribute this disparity to a perceived mismatch between European cultural norms and the alleged ‘Americanness’ of the megachurch (i.e. the valorization of bigness, consumerism, and popular leisure aesthetics), there is an alternative historical explanation as well: the ‘gospel of growth’, a long-standing theological emphasis within American evangelicalism on the imperative need and divine sanction for strenuous evangelism and continual harvest of souls. Embraced by revivalists, social gospellers, fundamentalists, black evangelicals, pentecostals, Southern Baptists, and a host of others, the ‘gospel of growth’ outfitted many American evangelical subcultures with a characteristic emphasis on the importance of congregational size, an emphasis largely absent among their European evangelical counterparts.