The rise of participatory democracy in urban Latin America has increased citizen deliberation in local politics, improved access to state officials and given residents greater control over municipal budgets. Simultaneously, welfare state retrenchment across the region has ensured the continued importance of the informal sector in securing citizen livelihoods, including informal political arrangements such as clientelism. Given their documented co-existence, how do informal political strategies operate in this new landscape of formal, local democracy? To answer this question, this article analyzes 21 semi-structured interviews with urbanists in Mexico City who evaluate the informal tactics of two groups that mobilize through participatory democratic initiatives: street vendor unions and white collar neighborhood councils. Urbanists regularly denounce informal, corporatist-clientelistic political strategies when they are used by street vendor groups. However, when deployed by white collar neighborhood councils, these tactics are tolerated and even celebrated. The differential reception of informal political tactics by city officials draws attention to how they construct the legitimacy or illegitimacy of informal political action. I argue that considering legitimacy adds a new analytical category to studies of informal politics that captures which groups are able to use informal tactics to advance their claims in local participatory democracy.