Interdict is the deprivation of people, communities, or a country from the church or the services provided by the church, such as baptism, marriage, and burial according to religious procedures, by the pope or the clergy authorized by the pope. These prohibitions may remain for a certain period or continue for many years. The interdict was initially seen as a reforming effort and was later used as an authoritarian power. The practice of interdict, seen as a kind of mitigation of the punishment of excommunication, started in the 10th century. It is seen that the practice became established with this name in the XII century. Medieval -especially the 12th and 13th centuries- is when the interdict was developed and used extensively by popes. The interdiction punishments to England and Leon in 1198, Normandy and France in 1199, France in 1200, and England in 1208 took place in the history books. This article gives information about interdict, a relatively neglected subject in the History of Religions in Turkey. Thus, it deals with the definition of the interdict, its distinction from excommunication, its development, and its use by popes.