The present paper embarks on the study of Persian cleft construction within the framework of Role and Reference Grammar (RRG henceforth). RRG intends to investigate the interaction of syntax, semantics and pragmatics via the constituent, logical and focus structure as independent but interrelated domains of the paradigm. To start with, an attempt will be made regarding demonstrating the specification role of the cleft construction, which is a universally semantic property of the construction, in the syntactic, semantic and information structures. In Persian clefts, despite that the clefted constituent is the semantic argument of the predicator of the cleft clause, it bears the role of pragmatic predicate assigned by the matrix predicator and the optional presence of the cleft pronoun as well, originating from the non-isomorphic nature of the cleft construction which expresses a single semantic proposition through a bipartition syntax. Given that the copula does not agree with the clause-initial cleft pronoun, albeit with the clefted constituent, and also that the matrix grammatical elements are considered to be merely focalizers, the so-called demonstrative, i.e. "in" is regarded as emphatic pronoun. The syntax-information structure interface in the cleftlike constructions in Persian, such as extraposition and preposed adverbials forms one of the central analyses of this paper where it will be displayed that RRG is much more equipped than the other theories to reflect the linguistic interfaces within various grammatical constructions. Of the most important findings is the necessity to distinguish the anaphoric "in", 'this' in the extraposition construction and the emphatic "in" 'it' in the cleft construction.