ENOn the basis of new handwritten documents, the author investigates the development of the gentry self government and the formation of the economic sejmik in the late 17th - early 18th century in various povets of the Grand Duchy of Lithuania. It was possible to establish that the economic sejmik owed its appearance to the “Republicans” movement, which saw as one of the points of its “equalization of rights” (koekwacja) program introducing of the skarb courts and transferring of the army funding in povets. On the economic seijmik should have elected: poborts (collectors) of czopove and sheleznoe, hibernoe, Jewish and Tatar pogolovnoe (capitation), tobacco monopoly, tax collection commissioners, as well as povet colonel and rittmeisters, composition of a skarb (fiscal) court. Keywords: economic sejmik, koekwacja, republicans, gentry, nobleman, collectors, skarb court, parliamentarism. [From the publication]