Focusing on the shadow education system of private supplementary tutoring, this paper contains comparisons over time and place in the distinctive circumstances of the Soviet Union and the 15 independent countries that emerged following its collapse in 1991. The paper uses the lenses of politics and economics to understand changing tides in the scale and nature of shadow education. The phenomenon did not fit the official ideologies of the Soviet era, but became evident particularly in the decades from the 1970s. In the post-Soviet era, shadow education expanded markedly, but with diversity across the 15 countries and with changing features as the decades progressed. The paper shows the broad contours in this diversity while also highlighting significant research gaps.