Joseph Stalin's personality left a giant imprint on the Soviet system. This chapter describes Stalin's relations with his deputies and their evolution into four phases. The first phase begins by assessing the rise of the Stalinist faction from the end of 1923 to 1924, when a solid majority formed within the Politburo against Leon Trotsky, whose impetuous behaviour and poor political judgement stoked up widespread unease within the leadership. The consolidation of dictatorship from the 1920s to the late 1930s and the operation of the Stalinist dictatorship at its peak, following the Great Purges, is the subject of the second phase. The third phase examines Stalin and his entourage during the war years, a period of marked decentralisation. The fourth phase discusses Stalin's last years, as the decision-making structures of the post-Stalin era. Although an important staging post on the road to dictatorship, the leadership system of the early 1930s is best viewed as a phase of unconsolidated oligarchic rule.