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	Religious Vitality Index	Religious Economies Analysis
Field	Sociology Of Religion	Sociology Of Religion
Family	Process / pipeline	Process / pipeline
Year of origin	1994	1987
Originator	Laurence R. Iannaccone	Rodney Stark & William Sims Bainbridge; Roger Finke
Type	Index/model of religious group strength via strictness	Supply-side economic analysis of religious markets
Seminal source	Iannaccone, L. R. (1994). Why Strict Churches Are Strong. American Journal of Sociology, 99(5), 1180-1211.	Stark, R., & Bainbridge, W. S. (1987). A Theory of Religion. New York: Peter Lang. ISBN: 9780820403564
Aliases	Church Strength Index, Strictness-Vitality Measure, Religious Group Strength Model, Free-Rider Vitality Index	Religious Market Model, Supply-Side Theory of Religion, Religious Economy Model, Rational-Choice Theory of Religion
Related	3	3
Summary	The religious vitality index operationalizes Laurence Iannaccone's celebrated argument, in his 1994 American Journal of Sociology article 'Why Strict Churches Are Strong,' that demanding religious groups are often the most vital. The seeming paradox dissolves once religion is viewed as a collective good vulnerable to free-riding: if members can enjoy the fellowship, enthusiasm, and mutual support of a congregation while contributing little, average commitment erodes and the group weakens. Strictness - costly, distinctive demands such as dress codes, time obligations, and behavioral prohibitions - works as a screening device that drives out the half-hearted and raises the average commitment of those who remain. The vitality index therefore models a group's strength as a function of its strictness, its members' participation, and its capacity to retain and mobilize committed adherents.	Religious economies analysis treats a society's religious life as a market in which competing firms (denominations, sects, and movements) offer products to consumers (potential adherents) under varying degrees of state regulation. Developed by Rodney Stark and William Sims Bainbridge in A Theory of Religion (1987) and elaborated by Stark and Finke in Acts of Faith (2000), the framework inverts the older secularization assumption that modernity erodes religious demand. Instead it holds that latent demand for religion is relatively stable, and that observed variation in religiousness across societies is driven mainly by the supply side: how many religious firms compete, how specialized and energetic they are, and how heavily the state regulates the market. Where competition is open and unregulated, vigorous firms mobilize participation; where one firm enjoys a state-protected monopoly, it grows lazy and overall participation falls.