In this article, I take a relational and discursive perspective on young children's self observed in daily natural conversations, and consider the process of semiotic mediation in the observer's recognition. Based on the ideas of co-construction of relationships and identities in conversation, and using excerpts of dialogues between a young child and her mother that deal with the child's experiences at daycare center ("hoikuen" in Japan) recorded during their car rides, I present how the self of young children in relation to others appears to observers. I regard this genre of self--"presentational self"--as a kind of Gestalt quality appearing in the act of positioning and in the configuration of the child and others presented through the conversation. As a basis of this process, I will discuss the semiotically mediated process of differentiation in 2 aspects of the conversation: first, in the process of conversation when the children and the partners make further extensions of what is shared, and second, in the array of self and others as exposed in the conversation.