This paper provides a systematic characterization of the organizational architecture of municipal governments in Mexico and how it varies with municipal size. Using detailed data from the National Census of Municipal Governments, the analysis documents patterns in the number of organizational units, staffing levels, sectoral specialization, and the allocation of budgetary and labor resources across functional areas. The results show that municipal bureaucracies expand initially through the creation of new units and, at later stages, through increased staffing within existing units, and that core functions such as public works, public services, and public security account for a large share of organizational resources. By describing these patterns, the paper helps address the scarcity of empirical evidence on the internal organization of the public sector and motivates further research on the relationship between organizational form and local state capacity.