Dedicated to the 250th anniversary of the Koliivshchyna, an uprising among Haidamakas in Right-Bank Ukraine in 1768, this article considers the question of the participation and role of Zaporozhian Cossacks. The author raises some fundamental terminological questions: who should be considered a Cossack in the context of the uprising? Why and how did so many Cossacks take part in the movement? What was their role? How did the Zaporozhian Sich and the Haidamaka movement relate to one another? And how did Koliivshchyna differ from previous uprisings? The author considers a number of archival sources which have not been studied previously and carries out comprehensive analysis of the Kodensky Book, the most important set of decisions taken by the Polish military court about the Haidamakas. The author concludes that the Zaporozhians, bearers of the “ideological” component of the Haidamaka movement, played a fundamental role. It is proved that the Cossacks played a key part in the Koliivshchyna, for which they were put on trial by both the Russian and Polish authorities. The author substantiates the fact that the participation of the Zaporozhians in the Koliivshchyna was the main reason for the disbandment of the Zaporozhian Sich after the end of the Russo-Turkish war.