The aim of this article is to explore the structure of social capital in peer networks and its relation to the unequal access of educational resources within mathematics classrooms. We hypothesise that learners can gain access to mathematics through friendship networks which provide more or less help from peers that might sustain (or curtail) their mathematics learning based on a Bourdieusian framework. We report a social network analysis of mutually-recognised helping within friendship groups. This is complemented by observation and interviews that illustrate how different classrooms have different network structures, positioning learners of different ethnic minorities and genders in significantly different ways regarding access to learning. We argue that friendship networks mediate social capital and access to further cultural capital, and that this may help explain structural differences in attainment. Because ethnicity and gender, "inter alia," mediate friendship networks, they also mediate access to capital in the classroom.