It is well known that strict churches are strong and growing in the contemporary United States, whereas liberal ones are declining. For Iannaccone's religious experience is a jointly produced collective good. Thus members of a church face a collective action problem. Strict churches, which often impose costly and esoteric requirements on their members, are able to solve this problem by weeding out potential free riders, since only the very committed would join the church in the face of such requirements. Consistent with the notion that religious experience is a collective good, Iannaccone et al. show that churches that extract more resources from their members (in the form of time and money) tend to grow in membership.