Why were left-wing politics so ineffective in Iran while socialism and communism were making great strides in the rest of the world? Why did the Left not capitalize on Iran's brief fling with anti-Western politics in the early 1950s before the Shah was restored to his throne? Above all, why was the Left so crushingly defeated after the 1979 Islamic revolution in Iran? Based on primary and secondary Persian-language sources never before published in English, this book reveals new details and provides fresh insights into an enduring puzzle of modern Iranian political history, concluding that the Left's demise came from a combination of Iran's geopolitical setting, where both the Soviets and the West saw advantage in the stability of Iran during the Cold War, and the Iranian Left's over-enthusiastic devotion to a barren Stalinism.