During the period of the common state of Serbs, Croats and Slovenes, several draft laws on religions and interreligious relations were drafted. One of the controversial issues that needed to be resolved was the regulation of religious conversions, i.e. procedures that members of one recognized religion had to follow when switching to another recognized religion. The paper analyzes all draft laws on interreligious relations with a special focus on the provisions governing the official conversion from one religion to another. The main hypothesis presented in the paper is that the interwar projects of the law on interreligious relations allow changing religious affiliation, but at the same time set a series of administrative obstacles that must be overcome by a person who wants to change the religious organization to which he belongs. Another hypothesis is that these administrative obstacles are a consequence of the specific regime of relations between the state and religious organizations, in which religious affiliation is not only a private matter for the individual, but also produces certain legal consequences in the form of specific obligations that members of a certain religion have towards their religious organizations.