Kulak, which derives from a term for fists or closed fist, had no real firm definition in the pre-revolutionary peasant milieu. The word was a derogatory term applied by other peasants to those members of the peasantry who had somehow gotten rich at other's expenses. Generally speaking, Kulaks were peasants in the post-Great Reforms period who were operating outside the Mir (commune, also called the obshchina) and acquiring land or farm animals without the oversight of the peasant community. Kulak did not have any specific class connotations in this context but rather was a descriptor for a number of behaviors against the community. Nor did the peasantry consider all rich peasants Kulaks. Studies of the existing evidence shows the term usually applied to peasants who took up root around a mir which they did not come from originally. This became more common with the Stolypin land reforms and the establishment of the peasant land bank which added a good deal of social disruption within the Russian countryside and allowed outsiders to buy up land.

The Bolsheviks took this very loose term and tried to make it an iron-clad social classification. One of the problems for Lenin and company was that the Marxist intellectual tradition of the time did not really concern itself much with matters of the countryside. Lenin's 1899 book Development of Capitalism in Russia argued that capitalism had taken root within the peasantry and divided up the peasantry into three classes: serednyaki (middling), bednyaki (poor), and kulaks (the rich). This tripartite division ignored the existing social organization of the peasantry as well as blaisely assuming that wealth was an indicator of peasant capitalism. This definition of a class-based peasantry was one of the reasons why the Bolsheviks' peasant policies were a general flop within the Russian countryside during the Civil War. Moscow's Committees for the Village Poor was to encourage the emerging class-consciousness of the peasantry and organize them in a campaign against peasant exploiters. The Committees generally failed at this task and the Bolsheviks were left having to accept the resuscitated Mir and the Black Partitions of the Revolution. The NEP period added a further confusing element as the state encouraged or allowed a form of peasant capitalism within the countryside. There were attempts by the state to encourage the bednyaki to act as a kind of rural proletariat and accord them privileged status in the nascent USSR, but these programs often fell short of funding or organization to match the state's propaganda of an alliance between rural and urban Russia. In the meantime, not only did peasant organization remain fairly robust in the face of Soviet attempts to regulate it, but there was a marked discrepancy between the tripartite classification of the state and the realities of peasant social organization.

One of the persistent undercurrents of the agricultural debates of the NEP period was that the Left Opposition and various factions around Stalin was a promise to get tough on the peasant Kulaks. This made the Kulaks a natural scapegoat and enemy during collectivization since the Soviet state could, and would, ascribe any peasant resistance to this class enemy. Poor peasants defending their seed grain and animals could suddenly become evidence of Kulak exploitation. This was what made collectivization so violent; the Soviet state had a dogmatic vision of the peasantry that did not match its social reality.