This thesis investigates the process of the construction of paid police services inthe port region of Rio de Janeiro between the end of the 19th century and the first decadesof the 20th century. It analyzes the history of two types of paid guards that operated in thecity: the trajectory of the night guards from their emergence in the 1880s, and the lifecycle of the Cais do Porto Police until the state attempted to take it over in the 1930s. Bypulling together different historiographical fields (the history of the police and securityforces, the history of the commercial and port labor world, and the social history of thecity), the project aims to fill a gap in historical knowledge about paid surveillance,security as a commodity, and the heterogeneity of policing forms that coexisted in the cityof Rio de Janeiro during the formation of a republican police system. The state-centricperspectives of police studies have characterized the emergence of the modern police as a process marked by the transfer of private coercive powers to the state and itspublic security forces, which continued until the rise of private surveillance companiesat the turn of the twentieth and twenty-first centuries. In dialogue with a renewedinternational historiography of private security, this thesis posits that the forms of paidpolicing in Rio de Janeiro were a constitutive part of the process of the emergence of therepublican police. This research demonstrates how professional law enforcement in Rioat the turn of the twentieth century was conceived as a mixed scheme between public andprivate dimensions of policing, interconnected in a zone of negotiation that broughttogether authorities, traders and surveillance workers. To this end, it analyzes a corpus ofpolice, literary, journalistic, and economic documentation. Far from taking Rio’s privateguards as dissociated from the expansion of the state coercive power, this thesis analyzesthem as part of a heterogeneous space for the exercise of coercion, paying attention to thenegotiated nature of their regulations, the state supervision of their daily activities and theworking conditions of their employees.