Since then, most of what has appeared have been accounts of the fall of the Soviet Union, in which Gorbachev is obviously a central player but not the sole focus — notably David Remnick’s exemplary “Lenin’s Tomb” and Michael Dobbs’s remarkable “Down With Big Brother.” There have also been academic looks at the man who ended the Cold War, like Archie Brown’s worthy “The Gorbachev Factor.” Gorbachev’s own memoirs were not especially satisfying and the series of other books he has written over the years seem more aimed at staking his claim as world statesman than revealing anything about the man and his moment.

So while a shelfful of books on Putin has appeared in recent years, Gorbachev largely disappeared, until now. Taubman took on the project with characteristic care. He benefited from archival research and the many memoirs written by people around Gorbachev, as well as the essential diary of Anatoly Chernyayev, one of Gorbachev’s closest advisers. He also conducted interviews with several key players, including eight sessions with Gorbachev himself over the course of several years. What emerges is the portrait of a leader who is vain, impatient and at times petulant, but also wise and thoughtful, a complicated man for a complicated time.

Born in 1931 near Stavropol in the North Caucasus, Gorbachev was close to his father, who fought in World War II, but had a more complex relationship with his mother, who was severe and whipped him with a belt. He worked five summers helping his father operate a combine harvester, earning the Order of the Red Banner of Labor, signed by Stalin himself, and wore it proudly throughout his first year at college. At Moscow State University, he was a country boy who did not even know what the ballet was.

But he was a quick study and became a master of the system he would later destroy, rising through the ranks as a provincial official in Stavropol. His real break was getting to know Yuri Andropov, another son of Stavropol, who became K.G.B. director and later general secretary of the Communist Party. The two were close enough that they vacationed together. Andropov brought Gorbachev to Moscow and into the Politburo, setting him up as an eventual successor in 1985. “We owe everything to him,” said Raisa Gorbachev, his wife.

From the inside, Gorbachev understood the system was rotting away. A turning point for him was the government’s knee-jerk cover-up of the Chernobyl nuclear disaster. “Chernobyl really opened my eyes,” Gorbachev said later. His life, he said, could be divided into two parts — before Chernobyl and after. His programs of glasnost, or openness, and perestroika, economic restructuring, changed Russian society. But his was a gradual, stutter-start revolution, a “revolution by evolutionary means,” as he put it.

Through the fall of the Berlin Wall, the summit meetings with Ronald Reagan and the changes in Soviet society, Gorbachev’s efforts to straddle between reformers and hard-liners satisfied neither side. His personal feud with Yeltsin sowed the seeds for his fall. Gorbachev, Taubman writes, may have recognized his own “arrogance, vanity, pride” in Yeltsin. “Gorbachev’s anger may have been aimed at least partly at himself.”

When the end came, as it inevitably would, the hard-liners turned against him first, mounting an amateurish coup attempt in 1991 that quickly fell in the face of popular resistance led by Yeltsin. But it was the reformers who finally did him in, as Yeltsin then shoved Gorbachev aside. Gorbachev’s final attempt at a comeback, a tragicomic run against Yeltsin, who was seeking re-election in 1996, yielded a humiliating 0.5 percent of the vote. That was the Russians’ judgment on the man who had been awarded the Nobel Peace Prize by the West.

When Yeltsin gave way to Putin at the start of 2000, Russia had changed, imperfectly, Gorbachev insisted, but still for the better. But it was turning again. “The truth is that Russia under Vladimir Putin largely abandoned Gorbachev’s path at home and abroad and returned to its traditional, authoritarian, anti-Western norm,” Taubman writes. “But that only underlines how exceptional Gorbachev was as a Russian ruler and world statesman.”