This chapter is a comparative investigation of the role of two major violence prevention interventions in South Africa and Brazil in building social cohesion and collective efficacy based on ethnographic studies of these programmes. Violence Prevention through Urban Upgrad-ing (VPUU) was implemented in the township of Khayelitsha in Cape Town, South Africa, while Pacifying Police Units (known by its Portuguese acronym, UPP) was set up in the favelas of Rio de Janeiro, Brazil.