This article investigates how 'prefigurative politics' and strategic interactions of undocumented migrant and solidarity movements shape different forms of political belonging. The overall objective is to show that the latest insights in social movement theory may help us understand how, when and why ambivalent notions of political belonging are enacted within such activisms. First, I argue that we need a social movement perspective of 'prefigurative politics' to grasp the autonomous performances of undocumented migrant and solidarity movements, and second that we need to problematise the contexts of these movements as dynamic, strategic interactions of various players, rather than static environments. Using empirical illustrations from the 'We Are Here' (WAH) movement in Amsterdam, I show that it is exactly in the ambivalent performance of prefigurative and strategic action that such social movements establish their complex and changing relations to regimes of in-/exclusion, and notions of political belonging such as citizenship. The empirical material in this article is based on qualitative interviews, supplemented with evidence from newspapers and internet materials.