This work investigates narrative practices developed by complainant and complainer in conciliation hearings at PROCON from two cities of Minas Gerais State. We assume that the storytelling framed by this setting has some characteristics that differs for example from the narratives told in spontaneous and other institutional contexts. Based on the intersection between Interactional Sociolinguistics and Ethnomethodological conversation analysis, we examine how shapes and functions of narrative constructions in this setting build and are built by the institutionality of the interaction. We focused on how complainant and complainer show different orientations about the responsibility for that damaging action, which is very present on narrative constructions at PROCON. Throughout narrative development, the disputants engage on a dispute over the definition of the situation making use of discourse strategies in order to present legitimacy and credibility to their narrations. We consider that the dynamic of identity formulations developed during narrations through evaluation elements is focused on strategic interventions used by the participants to shape their meanings about the facts. We also examine how the mediator`s institutional task during hearings is crucial for the development of narrative practices and construction and negotiation of the definition of the situation.