In this forum, three leading experts on Sino-Soviet relations and Mao Zedong’s policy toward the Soviet Union offer their appraisals of Sergey Radchenko’s Two Suns in the Heavens, The Sino-Soviet Struggle for Supremacy, 1962–1967, published by the Woodrow Wilson Center Press. The commentators praise many aspects of Radchenko’s book, but Michael Sheng and to a lesser extent Qiang Zhai and Deborah Kaple wonder whether Radchenko has gone too far in downplaying the role of ideology in Mao’s foreign policy. Unlike Lorenz Lüthi, who gives decisive weight to ideology in his own book about the Sino-Soviet split, Radchenko argues that a classical realist approach is the best framework for understanding Chinese foreign policy and the rift between China and the Soviet Union. Sheng and Zhai also raise questions about some of the sources used by Radchenko. Replying to the commentaries, Radchenko defends his conception of Mao’s foreign policy, arguing that it is a more nuanced view than Sheng and Zhai imply. Radchenko also stresses the inherent shortcomings of the source base scholars are forced to use when analyzing Chinese foreign policy.