Proponents of the supply side approach to religion theorize that religious market share-the proportion of people in a geographical area who belong to a given denomination-is inversely related to religious commitment in that denomination. They argue that a small market share motivates religious leaders to compete harder in the religious market place, increasing the participation of members. Another perspective, often associated with secularization theory, make the opposite prediction. It argues that people find it difficult to remain religiously committed in social environments where they are numerical minorities because other people do not reinforce their beliefs and practices. We use data from a large study of financial giving to analyze the relationship between market share and commitment for five denominations in the United States. We find that market share has a negative effect on church financial giving within all five denominations and a weaker negative effect on attendance in three of the denominations. We explore whether these effects are the spurious byproducts of pro-religious cultural norms associated with either the South or the presence of conservative Protestants in local areas. In models pooling all denominations, the negative effect of market share on financial giving and attendance cannot be explained away by either of these factors. However, the effect on attendance can be accounted for by congregational size.The growing importance of the "rational choice" perspective in the sociology of religion, particularly the "supply side" theories of Finke and Stark (1988, 1992Finke, Guest, and Stark 1996), has prompted interest in the relation between the composition of religious "markets" and religious participation. In general, Finke and Stark predict that religious participation and commitment will be highest in religious markets that are more competitive. They have proposed several indicators and/or causes of competition in religious markets, including religious pluralism, lack of state regulation of religion, and small market share. In this paper, we focus on market share, a religious group's share, or percentage, of all church members in a given geographic area. Finke and Stark (Stark, Finke, and Iannaccone 1995; Finke and Stark 1998; Stark 1997) argue that the smaller a group's market share, the greater the competition it faces, and the harder its leaders must work to increase membership and raise commitment levels if the group is to sustain itself. In contrast, groups with large market shares face little competition and may become "lazy," complacent about their hold over members and their sources of contributions.In addition to supply side theories, there are several other approaches that view small market share as a cause of greater religious commitment. These approaches suggest that small market share tends to heighten the "subcultural distinctiveness" of a religious group, making its members more dependent on the group for resources and/or more devoted to the values and beliefs supported by th...
