This article is devoted to the problem of children’s instruction on Islam in the Republic of Tatarstan. Research is based on fieldwork in several rural districts and six cities carried out in June and July 2017, as well as on the analysis of curricula, textbooks, and publications on religious educational reforms. The study shows that the main factor in how religion is taught in public schools is the multiethnic and multireligious composition of the population (54 and 44 percent of Tatar and Russian populations respectively). Of the six available modules for the study of religion and ethics, only two are taught in Tatarstan — Foundations of World Religious Cultures and Foundations of Secular Ethics. The remaining four — Orthodox, Islamic, Judaic and Buddhist Cultures — although widely taught in other Russian regions — are not utilized in the state schools of Tatarstan. This lack of religious instruction in public schools determines the intensity of children’s intrareligious education. The case of Islam shows the diversity of forms of children’s religious education: religion is taught in Muslim kindergartens, in special courses that operate near mosques, in summer camps, discussions and meetings with imams and Islamic clergy at schools, regular courses of Islamic ethics taught by imams at schools, and at Uthmaniya, the private general-education school founded in Kazan by the Tatarstan Muslim Religious Board. The case of Tatarstan, in which state and religious institutions have divided children’s religious education into spheres of influence, is an interesting example of building relations between religion and the state in post-Soviet, post-secular societies.