This paper studies the determinants of the unusually high and volatile price differential between common (voting) shares and preferred (nonvoting) shares in Russia's emerging stock market. It focuses on three potential explanations for the price spread between these two classes of stock: the control contest model of the voting premium, the inferior liquidity of preferred shares, and the risk of expropriation of preferred shareholders as a class. The regression analysis, based on data from 1997 to 2005, supports the control contest explanation and the liquidity argument. The hypothesis of expropriation of preferred shareholders as a class receives limited support, and only in the early period of the Russian stock market's development. The paper addresses the issue of structural breaks in the evolution of the price differential, related to the 1998 financial crisis and to improvements in investor protection in Russia in the early 2000s. It also provides new estimates of the magnitude of the private benefits of control in Russian companies.