The issue of the spread of Islam in the Balkans remains a historical problem that historians have not yet agreed on. In this research article, I investigated how Islam spread in Montenegro because of Ottoman politics in the sixteenth century. Based mainly on the Iskenderiye Mufassal Daftar and Mühimme, a kind of contemporary Ottoman official documents, I concluded that the Ottomans initially spread Islam in Montenegro through military and civilian officials, especially Muslim Ottoman soldiers employed in Montenegrin castles. It appears that Islam did not spread in Montenegro mostly by consent. The Ottoman administration seems to have followed a certain policy of its own for the consensual adoption of Islam by local people. The Ottomans wanted to make Islam permanent by providing tax exemption to new Muslims, granting those positions and rank, enabling them to save land, trying to reduce the pressure of Venice and the Catholic church on the local people, transferring the Muslim population from outside, and establishing foundations such as zawiyas and mosques. Despite all this, Islam encountered a great resistance in Montenegro due to the reaction of Venice and the old local feudal families.