Despite the proliferation of megachurches, it is unclear how the size of a religious organization affects its members. Two opposing assumptions are (1) size is a liability and (2) size is an asset. According to the first assumption, size negatively impacts the religious attitudes and behaviors of church attendees through the reduction of motivation and a loss of coordination (Hypothesis 1). According to the second assumption, a large church benefits from the economies of scale, and therefore size positively influences religious attitudes and behaviors (Hypothesis 2). A third possibility is that the outcome variables are curvilinearly related to size (Hypothesis 3). Using an Asian sample, we compared congregants from churches of different sizes to evaluate these hypotheses empirically. Analyses of cross-sectional and longitudinal data revealed that although churches of medium size (501–1,000 attendees) may be more successful in attracting and retaining believers more committed to their religion and positive about their congregation, they are no better or worse than smaller or larger churches in fostering religious commitment or building relationships among the congregants. Furthermore, our data showed that larger churches are more effective than smaller ones in preserving the “vertical” aspect of faith maturity. They are, however, less effective in fostering a sense of bonding among attendees. Thus, both Hypotheses 1 and 2 received partial support. A sweeping statement of whether being large is good for a religious organization and its attendees cannot be made.