摘要:The aim of this article is to discuss the distribution of preferences of members of the Chilean and Argentinian Congresso n foreign policy issues through the analysis of roll call votes. This goal is guided by the debate in Latin American literature concerning the decision-making process in foreign policy. The predominant argument focuses on the Executive as the principal decision-maker, disregarding the Legislative as relevant in this field. Thus, legislators would tend to abdicate from their preferences in determining foreign policy. Confronting this argument, we have many studies emphasizing the importance of domestic actors in the foreign policy decision-making process. This article proposes to analyse two case studies in comparative perspective: the lower houses of the national parliaments of Argentina and Chile. The result is that the party ideology is a relevant explanatory favor of deputies’ votes. Although the argument is more evident for the Chilean case, it is possible to argue that there is a similar pattern to the structuring of deputies’ votes in the two countries, both on the domestic and on the international arena. The methodology used makes it possible to infer legislators’ preferences by means of roll call votes and of the construction of maps of deputies’ ideal points in foreign policy terms, as well as the correlation between Chilean and Argentinian parties’ ideological classifications. Votes on foreign policy questions during the 2002-2006/2007 legislatures are considered.