This article discusses friendships and peer groups of migrant and minority ethnic youth in schools in England and Spain, and critically considers them in relation to existing notions of "peer social capital" and bridging (heterogeneous) and bonding (homogeneous) peer networks. The article argues for an extended understanding of peer social capital and discusses the complex composition and outcomes of bridging and bonding peer networks. It critically discusses both facilitators and barriers to friendships experienced by migrant and minority ethnic youth in schools, and considers them in relation to school practices.