This article examines specifically Bulgarian pronominal composita with possessive meaning made up of a full possessive pronoun and the clitic si (e.g., moya si, svoya si). The analysis highlights the positioning of such composita in the system of possessive pronouns, establishes their types, and accounts for their rivalry with simple forms of possessive pronouns. The semantic input of the clitic si is discussed, and techniques are proposed for adequate translation of such structures into Russian. Of typological significance are their delimitation from double pronouns, as well as morphological treatment of si as a particle rather than a pronoun, which contributes to the study of the multifunctionality of Slavic clitics and their linear syntactic characteristics.