Bureaucratic politics—for example, the “political” interaction between individuals and organizations in the executive branch of government—is a potentially significant force affecting the course and outcomes of governmental policymaking processes. In this article, an empirical and normative model and operationalization of bureaucratic politics is developed, treating it as a variable rather than as an immutable (and by definition problematic) property of policy decision-making. A conceptual model, linking the nature and intensity of bureaucratic politics in advisory systems to the characteristics of the political leaders served by them, is also developed. On the basis of earlier studies of presidential leadership (e.g., Preston, 1996), the leader's need for power, cognitive complexity, and prior policy experience/expertise are hypothesized to affect the organization and operation of the advisory system in terms of bureaucratic politics. Using Hermann's (1983) Personality Assessment-at-a-Distance (PAD) coding technique, theoretical assertions are illustrated in a detailed case study of two critical episodes in U.S. decision-making in the conduct of the Vietnam war in 1965 and 1968.