The children participation project "The City of Children" ("La Ciudad de las Ninas y los Ninos" in Spanish) emerged in Italy as an attempt to incorporate children as active citizens to the improvement of their cities through the designing and planning of urban areas. The project aims to provide real value to the children's voice and thus, to materialize their ideas. The main objective of this paper is to describe the implementation of the project in the cities of Rosario and Montevideo, highlighting the "Children Councils" (Consejos de Ninas y Ninos in Spanish) as a key instance of participation. Using qualitative analysis as well as inside-field-visit to both cities in which coordination teams were interviewed, the article is able to reach descriptions and features of the project. The results show that, far from being made exclusively for children, the "The City of Children" project underlines the importance of local government along with, the role of community, which becomes involved in the actions and receives the impact from the changes in the physical and social space.