The Russian colonization of the Kazak steppe was characterized by the seizure of Kazak grazing lands by voluntary Europeans, mostly Russian Cossacks and peasants. This process began soon after the annexation of the Kazak Younger Horde in 1731, long before the Kazak lands were officially declared state property given to the Kazaks for collective use in the Provisional Statute of 1868. The paper investigates this process of colonization. Special attention is given to the proceedings of the official commissions who tried, on the basis of "scientific" reasoning, to delimitate the amount of land required for the Kazaks and their flocks and thus to provide a rationale to hand all the "excessive" lands over to the settlers. It is based on the reports of these commissions, on archival sources and on contemporary Kazak material.