In order to study political rallies, it is first of all necessary to understand how parties are part of the evolving identities of urban spaces, and how belonging in specific ways to urban spaces in turn produces party allegiances and identities. Meetings are, furthermore, privileged observation points of the “partisan milieu” and of its constitutive ethos. Ethnographic analysis, combined with interviews, indeed allows a better understanding of the ongoing transformation of party militancy in Mexico: the rise of local organizations (the “territorial structure”) caught in a competitive relationship with corporatist structures in the case of the PRI; the emergence of independent entrepreneurs of mobilization in the case of the PAN in spite of the strength of its party apparatus; the diversity of militant networks and their loose relationship to the party label in the case of the PRD. This study also highlights the variations of militant sociability with regards to parties, as well as the variable importance of family-based or affinity-driven networks of sociability. Lastly, this study of rallies was also the occasion to put under close scrutiny the “moral economy” of mobilization, hence to devote special attention to the ambivalent beliefs and values that people invest in so-called “clientelistic relationships” with local party leaders.