The use of a model proposed by John Zaller shows that the process Of opinion formation in matters pertaining to foreign policy is similar to that observed in related areas such as immigration and security us well as in specifically internal policy matters. The model is applied to the study of Swiss electors surveyed at the time of federal referendum campaigns covering fifteen years. It is found that the level of support for the proposals is a function of the level of political consciousness and political predispositions of the individual voter on the orle hand, and of the degree of disagreement among the elites on the other. The formation of opinions on foreign policy matters finds its specificity in the conditions that characterize campaigns that differ in terms of intensity, level of conflict, and party alignment.