Iannaccone (1994) claims that members of churches with strict rules (e.g., no smoking or drinking) have higher average commitment because strict rules discourage involvement by less committed potential members. Most previous studies of Iannaccone's assertions have studied congregations within a single denomination, and these studies have found little support for his claims. However, Iannaccone (1996) has responded that strictness is primarily a characteristic of denominations that varies little within a single denomination. If true, multidenominational studies are needed to detect the potential effects of strictness. Using data from a five-denomination, 625-congregation study, we find that within each denomination, strictness is not significantly related to measures of commitment. However, we also find, as Iannaccone claims, that most of the variation in strictness occurs between, rather than within, denominations. Thus, when we examine data from all five denominations, we find that strictness is strongly correlated with several important measures of member commitment levels.