Who makes foreign policy decisions? What is the effect of the decision unit on the resulting foreign policy? An examination of how governments and ruling parties make foreign policy decisions suggests that authority is exercised by an extensive array of different entities. Among these decision units are prime ministers, presidents, politburos, juntas, cabinets, interagency groups, coalitions, and parliaments. Moreover, within any one government the pertinent decision unit often changes with time and issue. When cross-national comparisons of governmental decision-making bodies are contemplated, as in the comparative study of foreign policy, the number of possible kinds of decision units becomes formidable. In the project on which this chapter is based, we are exploring one way of classifying decision units. 1 Of particular interest are the circumstances under which one type of decision unit takes responsibility for making the choice regarding how to deal with a foreign policy problem and the effect of the nature of the decision unit on the substance of the action selected.