Based on two studies carried out in the cities of Buenos Aires and Montevideo and additional research in Brazil, this report examines the origin, characteristics and impact of the explosive increase in consumption of cocaine base paste and crack in urban areas. The question of whether there is a cause-and effect relationship between the explosive increase in consumption in Argentina, Uruguay and Brazil and a transformation in the structure of cocaine trafficking in Argentina, Uruguay and southern Brazil is relevant to an evaluation of the success of failure of policies implemented in the Andean Region to stem the supply of cocaine.