This study aims to analyse the interactional construction of fictional accounts produced by dyads of 4- year-old children from marginalised urban populations in Argentina. The narratives, elicited from a sequence of images, were video-taped and transcribed. The data corpus consist of 33 narratives produced by dyads of 4 yearold children. A qualitative analysis was performed that combined the Constant Comparative Method (Glaser & Strauss, 1967; Strauss & Corbin, 1990) with tools from Conversation Analysis (Goodwin 1984, 2007; Sacks, Schegloff & Jefferson, 1974). This analysis allowed the generation of a system of categories that identified the narrative roles assumed by the participants. The analysis attended to the juxtaposition of different semiotic fields: linguistic information, body position, intonation, gaze direction, gestures and the manipulation of objects. Findings showed that children adopted roles of storyteller, audience, or parallel player. In most of the cases both children adopted a storyteller role leading to a negotiation process that allowed them to co-construct the narrative.