In this roundtable, four of international relations’ finest scholars evaluate Marcus Holmes’s Face-to-Face Diplomacy: Social Neuroscience and International Relations, a bold effort to bring research on brains to bear on questions of high-stakes summitry. While international relations scholars identify uncertainty, particularly the problem of judging the intentions of other states, as a central and essentially unsolvable problematique, Holmes disagrees. Research shows that our neural architecture is set up to simulate the mental states of others when we meet face-to-face, something that we do unconsciously and intuitively. Holmes draws the conclusions of this central claim for the study of diplomacy, a process that is finally receiving the theoretical and empirical attention it deserves. All of the reviewers agree that this interdisciplinary-inspired book offers a new look at an old question of international relations. Andrew Ross writes, “Holmes leverages this account of intersubjectivity to dismantle an entire edifice of theorizing built on the problem of other minds, inaccessible intentions, and the distrust that ensues therein. The result is a potential game-changer not only for the study of diplomacy but also for efforts to understand other forms of social interaction in international affairs.” They also praise him for his adroit use of history. The book explores the power of face-to-face diplomacy in case studies that include the interactions of presidents Ronald Reagan and George H.W. Bush with Soviet premier Mikhail Gorbachev, the Munich summit between British prime minister Neville Chamberlain and Nazi Germany’s Adolf Hitler, and the Camp David summit in which President Jimmy Carter brokered peace between Egypt and Israel.