The article investigates factive predicates in the Balkan languages, focusing on the types of conjunctions/complementizers that introduce subordinate clauses selected by these predicates. Building on the classical typology of factive constructions (Kiparsky, Kiparsky 1970; Karttunen 1971; Karttunen 1973; Karttunen 1974), I show that in the Balkan area, alongside declarative complementizers and subjunctive particles, there also exist specialized factive complementizers (Bulgarian deto, Serbian/Croatian što, Greek pu). These complementizers are selected exclusively by emotive predicates and correlate with the projection of presupposition in the embedded clause, as well as with a range of additional syntactic effects. The article delineates the parameters of these phenomena in Bulgarian and places them in a comparative perspective with respect to existing research on factivity, clause types, and the nominal nature of embedded structures. In conclusion, the paper dis-cusses specific aspects of the development of these complementizers in the Balkan languages and their role in expressing factivity, in contrast to languages such as English, which employ a single complementizer across all predicate types.