As an Iranian Muslim woman and a granddaughter of a well-known ayatollah, Shahla Haeri was accepted into the communities where she conducted her fieldwork on mut’a, temporary marriage. Mut’a is legally sanctioned among the Twelver Shi’ites who live predominantly in Iran. Drawing on rich interviews that would have been denied a Western anthropologist, the author describes the concept of a temporary-marriage contract, in which a man and an unmarried woman (virgin, widow, or divorcee) decide how long they want to stay married to each other (from one hour to ninety-nine years) and how much money is to be given to the temporary wife. Since the Iranian revolution of 1979, the regime has conduction an intensive campaign to revitalize this form of marriage, and Shi’i ulama (religious scholars) support it as positive, self-affirming, and cognizant of human needs. Challenged by secularly educated urban Iranian women, and men and by the West, the ulama have been called upon to address themselves to the implications of this custom for modern Iranian society, to respond to the changes that mut’a is legally equivalent to hire or lease, that it is abusive of women, and that it is in fact legalized prostitution. Law if Desire thus makes available previously untapped and undocumented data about an institution in which sexuality, morality, religious rules, secular laws, and cultural practices converge. This important work will be of interest to cultural anthropologist, religious scholars, scholars of the Middle East, and lawyers as well as to those interested in the role of women in Islamic society.