The first section describes the organization of the Metro Protection and Security Police: their shifts, the composition of their teams, their distribution, and their interaction with crime specialists. The following section describes police interaction with the public--what obvious or latent cues prompt police to halt suspicious characters, drug traffickers, unlicensed vendors, or vagrants; how those detained react; and how bystanders respond to police intervention. Two sections are devoted to the activities of plain-clothed police officers as opposed to those in uniform. Plain-clothed officers specialize in detecting drug operations and thefts while uniformed officers cause small offenders to betray themselves by running away. The article concludes that the officers in the metro, like other specialized forces, have their own concept of order and security, which is linked to both the specific criminality of the subway and the high visibility of police intervention.