The author examines the paradox of Mikhail Gorbachev's esteem for Lenin in combination with his growing rejection of Leninism. While Gorbachev still held the office of general secretary of the Soviet Communist Party, he embraced ideas fundamentally at odds with those of the Soviet Union's principal architect. The focus of Western writers on Gorbachev's 1987 book, Perestroika: New Thinking for Our Country and the World, as a major source has been simplistic and misleading, obscuring the radicalization of Gorbachev's political ideas from 1988 onward. Drawing, inter alia, on previously unused archival documents, the author demonstrates how Gorbachev's views moved closer to those of Eduard Bernstein, a democratic socialist thinker whom Lenin despised, than to Leninism. Given the institutional power Gorbachev wielded until late in the perestroika period, his embrace of concepts radically at odds with Leninism was of critical importance, opening doors which had remained firmly closed for decades.