This paper analyzes the application of the compulsory subdivision, construction, and utilization of land, which requires owners to comply with the social function of urban properties. The article discusses the structural regulatory framework under the Brazilian Federal Constitution and the City act (Federal Law n. 10257/01) governing this legislation, as well as the specific case of Santo André, a municipality in the São Paulo metropolitan region. In 2006, Santo André began to notify owners of vacant and underutilized land, using specific criteria and procedures in the regulation and application of the above legislation. By the end of 2008, nearly 26 percent of the owners of all selected properties were notified, with about 65 percent located in the area of the Tamanduateí Axis. The monitoring process that took place from 2006 to 2008 identified several hurdles in the application of this instrument, such as legal, title, and record issues, the governability of local stakeholders, and difficulties in combining requirements such as subdividing and building in restricted-zoning areas. The Santo André experience also provides material for discussion of the frailness of the pact built to apply this instrument during the preparation and approval phases of the city's master plan as well as for understanding several issues that might be common to the urban policies of cities opting to use this legislation.