Firstly, this paper exposes the meaning attributed by Karl Kautsky to the Protestant Reformation. This is not only understood as the beginning of the era of social revolutions, but it also represents, formally, the way in which the next socialist revolution will occur. Secondly, the paper analyses the difference between reform and revolution on the basis of some reflections of Karl Marx and Rosa Luxemburg. It emerges that the revolution (the “reversal” of relations of production) is understood as the purpose of a process in which the reforms constitute the intermediate moments and consequently the means for that purpose. But against this scheme, the word “reform” no longer indicates in the current political language a measure that approaches that end purpose; it indicates rather a measure that moves away from it. Even though it is presented as a (necessary) innovation, it is in fact a regression.