The article presents a brief historical survey of the main opinions about the impersonal constructions in Bulgarian. It also offers a classification of the impersonal predicates, based on several formal criteria: the predicate type – VP (reflexive/non reflexive), AUX + NP, AUX + AdvP, AUX + PP; their combinations with accusative and dative objects; their possibility/impossibility to participate in constructions with explicit subject.