is one of the world's most violent regions, with 40 of the 50 most violent cities, but with only 8% of the world's population, and a staggering 33% of global homicides. At the forefront of these high levels of violence are gangs that are more flexible and persistent than previously thought. This paper provides a discussion on gangs in one Latin American city, Medellin, Colombia, where different non-state groups have contributed to changing patterns of homicide rates. The paper presents preliminary findings to show how, despite the city experiencing a 90% reduction in homicide rates in less than 25 years, violent non-state groups have become embedded as part and product of their environment, acting as coherent, logical and functional players, linked to the structural inequalities and institutional fragility of the larger society.