One of the main concerns in policy making in general and foreign policy making in particular is the problem of inappropriate decisions, i.e., a decision that is unlikely to lead to set objectives and may even result in negative consequences. There is no guarantee for the success of decisions due to feedback aspects and the multiplicity of other actors whose actions and reactions are not totally predictable. Yet it is possible to reduce the possibility of irrational/inappropriate decisions through recognizing the factors that can lead to bad decisions. This article suggests a rational model of decision making in foreign policy and then, on the basis of IR theories and theories of foreign policy shows the factors that can interfere in rational policy making. It is argued that cognitive factors are more influential because most other elements can be reduced to cognitive ones.