In this paper I look at how through the use of teasing as a socially recurrent activity the members of a multilingual, multicultural and multiethnic peer group (comprised of majority Greek and minority Turkish-speaking children of Roma heritage) make particular identity ascriptions and displays salient and position themselves and others in particular ways in peer talk during break-time in an Athens primary school. Taking as a point of departure that identities are produced relationally, through systems of opposition (Barth 1969), the paper deals with how members of this school-based peer group exploit teasing as a versatile discursive device to construct one particular peer as a “poor” pupil and themselves by extension as “good” pupils in talk-in-interaction. The focus on the situated and relational construction of identity makes visible how children position themselves with regard to others in order to construct academic hierarchies. At the same time, it brings to the fore how through such positionings children may reproduce but also challenge powerful institutional discourses of academic success and failure in circulation in the classroom by negotiating identity options closer to their peer concerns. These processes of identity construction demonstrate how social selves are produced in interaction through contestation and collaboration and how identities may be simultaneously chosen and imposed through language use.