Students of international politics often state that power is to us what money is to the economist: the medium via which transactions are observed and measured. Further, there seems to be a solid consensus that power is a useful concept only in its relative sense; such objective measures as military manpower, technological level, and gross national product are viewed as helpful, but incomplete, indices. The concept does not come to life except as it is observed in action, and that action can be found only when national power is brought into play by nations engaged in the process of influencing one another. Until that occurs, we have no operational indices of power, defined here as the capacity to influence. In this paper, then, my purpose is to seek a clarification of the concept of power by the presentation of a formal, analytic model of bilateral inter-nation influence.