How relevant are the Big Five in predicting religiosity? Existing evidence suggests that the Big Five domains account for only a small amount of variance in religiosity. Some researchers have claimed that the Big Five domains are too broad and not sufficiently specific to explain much religiosity variance. Accordingly, they speculated that the more specific Big Five facets should predict religiosity better. Yet, such research has generally been sparse, monocultural, descriptive, process-inattentive, and somewhat contradictory in its results. Therefore, we conducted three large-scale, cross-cultural, theory-driven, and process-attentive studies. Study 1 (N = 2,277,240) used self-reports across 96 countries, Study 2 (N = 555,235) used informant-reports across 57 countries, and Study 3 (N = 1,413,982) used self-reports across 2,176 cities, 279 states, and 29 countries. Our results were highly consistent across studies. Contrary to widespread assumptions, the Big Five facets did not explain substantially more variance in religiosity than the Big Five domains. Moreover, culture was much more important than previously assumed. More specifically, the Big Five facets collectively explained little variance in religiosity in the least religious cultural contexts (4.2%) but explained substantial variance in religiosity in the most religious cultural contexts (19.5%). In conclusion, the Big Five facets are major predictors of religiosity, but only in religious cultural contexts. (PsycInfo Database Record (c) 2020 APA, all rights reserved)