Violence is a priority problem in Colombia. Although violence has been traditionally approached from the perspectives of law and order, the tools of public health may also be used to contribute to solving this problem. Public health proposes a four step approach to prevent health problems: (1) defining the problem, (2) identifying its causes, (3) developing and evaluating interventions, and (4) disseminating effective interventions for wide-scale implementation. This paper describes how these methods were used to approach this problem in the city of Medellín.