Two external possessor constructions occur in ancient Indo-European languages: the dative external possessor construction, and the double case construction. They both indicate adnominal possession by means of syntactically independent NPs, and basically refer to inalienable possession. In this article, I analyze the two constructions, describe their meaning and their syntactic properties, and review the comparative evidence for each of them. Neither construction is uniformly attested throughout the Indo-European language family. In addition, the dative external possessor construction seems to be quite unstable over time. Based on the data presented, I conclude that the former can be reconstructed as an original Proto-Indo-European construction, while the latter must be regarded as a language specific construction, with different properties in the languages in which it occurs.