Subject of the investigation is the phenomenon of ancient hostage-taking from the 4th century B.C to the time of Augustus. Since foreign princes served as guarantors for different kind of treaties and therefore for the good behavior of their fathers, they also received a kind of education: Therefore the term educatio principum runs like a golden thread through the dissertation. The sources report that the children served as security to an agreement and later on as loyal vassals. Unfortunately, they do not report the means by which a former hostage was made a loyal ally. To answer this question, the first part of the paper examines the hostage-taking in the context of the political history. Subsequently, the hostages are analyzed by the means of epistemological issues. The age of the hostage, the duration of the hostage-taking and the social intercourse plays an important role. Noteworthy, however, is the role of education and, consequently, the transfer of knowledge.