In this paper we present a brief analysis of urban demographic growth in Latin-America, in order to understand the nature of the process in recent years. According to United Nations statistics, the process of urbanization in Latin America has been remarkable in recent years (41% of its population lived in cities in 1950, in 2000 reached 78% and in the next 40 years it will rise over 80%). Still, these countries have experienced different paces of urban growth, being in different stages of urbanization (or urban transition). The particular case of Colombia will be analyzed as a country that has undergone a later urbanization process (after 1930) and has urbanized very quickly. The main reason for this rapid process of urbanization is the disadvantaged economic and social conditions of rural areas in association with civil violence which characterizes the process of urbanization in some Latin-American countries. Both facts brought specific problems for Colombian cities that local governments have been trying to solve in the last 20 years. The case of Medellin will be presented as a city that some authors associate to the so called Models of Urban Cultural Development. The social urbanism of Medellin is presented as a tool to promote inclusion through education and huge investments in the public degraded areas of the city. We will present some of these interventions, their purposes and effects in the improving of urban life.