n this paper we propose a modelization of the construction of Persian noun and adjec- tival phrases in a phrase structure grammar. This modelization uses the Interaction Grammar (IG) formalism by taking advan- tage of the polarities on features and tree descriptions for the various constructions that we studied. The proposed grammar was implemented with a Metagrammar compiler named XMG. A small test suite was built and tested with a parser based on IG, called LEOPAR. The experimental results show that we could parse the phrases successfully, even the most complex ones which have various constructions in them.