Spain's Social Settlement regularization program is a prima facie inclusive policy that allows irregular immigrants to acquire residence permits after 3 years of continuous residence. The only acceptable proof of residence is registration on a municipal census. Each municipality is enabled to designate its own housing requirements for registry on its census, which disproportionately impact racialized irregular immigrants. Given this highly decentralized legalization model, the guiding question of this dissertation is: how do municipal rules structure irregular migrants' regularization opportunities and outcomes? Using a most-similar case design and interviews with Malian immigrants in two rural municipalities with different census regulations, I illustrate how the variation in requirements creates different opportunities and challenges for racialized irregular migrants attempting to regularize their legal status according to their respective locality. Since housing and the municipal registry are inextricably linked, racial discrimination in the housing market disproportionately diminishes the opportunities for Black irregular migrants to regularize their legal status in some municipalities, trapping them in a cycle of irregularity that impacts their individual and collective economic mobility, civic stratification, and family structure via family reunification policies. By continuously failing to provide national standards for municipal census requirements, the state thereby allows some municipalities to facilitate regularization and others to discreetly impede it. The varied experiences of immigrants with the municipal census and the regularization process in Spain exemplify the local mechanisms of exclusion that reinforce civic stratification even in the face of national inclusion measures. As such, municipal census policy not only has significant implications for immigrants' long-term political integration, but it is also instructive for how race and local policy shape citizenship.