The history of the Reformation in Poland has been an object of interest to historians since the nineteenth century. The fundamental questions in the research into the Reformation and Protestant communities include how to interpret and periodise their history in Polish territory. Historians have suggested diverse, at times contradictory, periodisation options, beginning with 1517 – the year of Martin Luther’s protest and his ninety-five Theses, and pointing to an end of the Reformation in Poland somewhere between 1573 and 1608. The article briefly recapitulates the milestone publications in the history of the Reformation in Poland as well as the most important historical discourses around the issue.