If institutions are important for regulating violence, can institutional reforms make societies less violent? This article examines the north-east Brazilian state of Pernambuco primarily between 2007 and 2013, proposing that patterns of declining lethal violence can be explained by changes in both the accountability and effectiveness of formal state institutions and informal social norms. Drawing on two months of qualitative fieldwork, findings suggest that social and political mobilisation enabled a political coalition to initiate substantial changes under the Pacto pela Vida (Pact for Life) public-security programme, which improved the legitimacy and operational effectiveness of the criminal justice system, and coincided with a marked reduction in homicide rates. While showing that these reforms were central in reducing lethal violence in Pernambuco between 2007 and 2013, the article concludes by discussing the challenges of policy continuity in light of increasing rates of lethal violence since 2014.
