South Korea has emerged as a new middle power that plays a significant role in a wide range of important global issue areas and supports liberal international order with its leadership diplomacy. Even though regional challenges will continue to demand large foreign policy resources including time, human resources, and budget, the middle power orientation of South Korean foreign policy behaviour and strategy—for example, multilateralism, the rule of law, and promotion of cooperation and compromise—will remain in place even in the conduct of regional foreign policy. This optimism is based on the fact that South Korea is a middle power not only in global governance but also in the East Asian region. Even on the issue of North Korea’s nuclear weapons, the most important foreign policy challenge of the day, the South has accepted the regionalization of the issue and, over time, its middle power role. It has relied on the middle power strategy of mobilizing international pressure on the North rather than deploying and strengthening its unilateral options such as the use of force or massive economic aid. In order to fully realize the promise and potential of middle power diplomacy, however, South Korea must make strong efforts to alleviate structural constraints on a middle power strategy. First, Korean leaders should undertake a full-scale campaign to de-nationalize Korean education and, thus, Korean foreign policy orientations. Second, a strong domestic consensus should emerge giving the national interest precedence over group interests when dealing with foreign policy challenges. Finally, political leaders and diplomats must create new opportunities in global governance and deliver tangible national benefits through middle power diplomacy. Middle power diplomacy, like all foreign policy strategies, will not be sustainable without strong domestic support; and domestic support cannot be built on goodwill and commitment to universal values alone.