In 2008, Rio de Janeiro began to implement a policing program known as "pacification" in select favelas throughout the city. This controversial program, part of a larger public security effort ahead of the 2014 World Cup and 2016 Summer Olympic Games, aimed to regain control of these territories from heavily armed drug traffickers. It marked a new approach to policing the favelas: a shift from siege-style operations toward proximity policing via the establishment of a Pacifying Police Unit (UPP) in these territories "regained" by the state. Beyond the challenge of driving out the armed traffickers who dominated these areas, the program faced that of overcoming a history of police violence and corruption, and of mutual prejudice between police officers and favela residents. Favelas dominated by drug traffickers are an example of what Guillermo O'Donnell (1993) calls "brown areas." Brown areas are territories within a state where democracy is not yet fully consolidated, and informal, privatized but highly efficient (often violent) legal systems prevail in light of the sporadic presence of the formal legal system. Pacification represents an opportunity to look at brown areas in transition, where the state is trying to undermine the informal system of power and replace it with the formal, thereby fulfilling its duty to protect the rights of citizens in these areas. Little is known about what transition looks like in brown areas. What causes it to succeed in some areas but fail in others? How can informal, deeply embedded systems of power be effectively replaced? How are communities affected by this transition? I will conduct a year-long comparative ethnography of four pacified favelas during the crucial period surrounding Rio's hosting of the 2016 Summer Olympic Games. One of these cases I have been following since May 2012. I will employ within-case analysis to identify mechanisms and processes at work in this transition and cross-case analysis for added leverage.