This dissertation investigates the syntax of the be-possessive and its extension to the perfect construction that encodes ergativity in North Russian, in the context of parametric variation. In this study, seemingly unrelated phenomena such as perfect, obligation, and ergative constructions are construed as extensions of possessive structure involving be, as the consequence of the have/be parameter.

One primary claim on the underlying structure of the be-possessive in Russian is that the possessor is base-generated as an external argument, whereas the possessed noun is generated as a predicative nominal in a DP structure embedded under the copula. This view is supported by Russian data indicating the lack of predicate inversion in this construction. Another crucial component of the structure is a low focus phrase, which is independently supported by relatively free word order that is sensitive to information structure. The cross-linguistic have-/be-possessive alternation is viewed as depending on a language's functional inventory, including a prepositional complementizer with or without Case feature.

The proposed structure of the Russian be-possessive construction directly feeds the account of the syntax of the be-perfect in North Russian. The perfect construction appears to be a parametric variant of the possessive structure in terms of the nature of the embedded clause: DP in the possessive vs. CP in the perfect. The be-perfect structure entails ergativity via distinct degrees of nominalization of the participle phrase. The micro-variations in Case and Agreement in this construction are accounted for as a consequence of parametric difference of the categorial nature of the lowest functional node.

The most crucial innovation in the development process of the North Russian perfect from a possessive sentence embedding a passive small clause is construed as the change of the argument structure of the small clause (i.e., voice shift) along with the change of the semantic contents of the possessive phrase and its syntactic mapping. The voice shift was triggered by the change of the argument status of the possessive phrase from a benefactive applicative to an agentive external argument.