No Western publication on international investment law (IIL) has ever specifically undertaken a comparative study of Russian and Western doctrines of IIL. Although Russian scholars often contrast Western and Russian approaches to international law, scholars in the West mostly proceed without any discussion of Russian practice and perspectives. To fill this gap, this essay introduces the Russian approach to IIL and contrasts it with its Western counterpart. In particular, we show that the Russian approach focuses far more extensively on the nature and categorization of IIL and treats IIL primarily as private international law rather than public international law. The distinctive Russian approach has practical relevance for states and scholars, in part because it helps to explain why Russia has resisted efforts to reform investor-state dispute settlement.