The term “national interest” has been used by statesmen and scholars since the founding of nation-states to describe the aspirations and goals of sovereign entities in the international arena. Today foreign ministers, military strategists and academicians discuss the vital interests of their countries in ways suggesting that everyone understands precisely what they mean and will draw correct inferences from their use of the term. Nothing could be further from reality. In truth, the study of international politics as well as the art of diplomacy suffer from widespread ambiguity about the meaning of national interest, with the result that some scholars have proposed that the concept be abandoned and replaced by some other phrase. To my mind, this would be an abdication of the scholar's responsibility because, whether we like it or not, the term national interest is so deeply ingrained in the literature of international relations and diplomatic language that it is unlikely to be dismissed from our vocabulary simply because some scholars find it useless. Were we to attempt to substitute some new phrase, we would likely find even less consensus and could become engaged in yet another round of jargon-creation. A better alternative, I suggest, is to strive for a more precise definition of national interest and then provide a conceptual framework in which serious discussion of foreign policy and international politics can become more fruitful. That is the purpose of this paper.