In contrast to the tolerant and largely peaceful ‘living politics' of informal settlements, as embodied by the social movement Abahlali baseMjondolo, this article considers a darker side of squatter politics: ‘xenophobic’ mobilization. I show how the historical stratification of citizenship in South Africa remains spatially embedded in longstanding informal settlements, where distinctive repertoires of collective action have been shaped by a (still unfinished) history of struggle for inclusion. Using archival research and interviews conducted in the informal settlements of Atteridgeville, Gauteng, I show how the continuing struggle for equal citizenship draws on shared experiences of mundane hardship and collective labour, giving rise to social distance between established local squatters and politically indifferent foreign newcomers. At times of protest, this polarity is concentrated by and converges with familiar practices of insurgent citizenship, creating a context for mobilization against foreigners. In this sense, ‘xenophobic’ mobilization may be seen to articulate a claim for inclusion by structurally excluded ‘citizens', rather than an exclusionary claim by those who already belong. The article provides a useful counterpoint to readings of ‘xenophobic’ violence that focus on the role of elite discourses, instrumental leaders or crude racial identities in shaping such mobilization.