A majority of human beings live in cities, half of them in cities of less than 500.000 inhabitants, and around I billion of dwellers live today in slums (meaning 25% of urban residents in the global South). Having these numbers in mind, the main question for urban planners and decision makers is: why our forecasts of a sustainable urban development have not been reached, at least not for all people, what may we change in order to create and enhance “smart cities” offering access to infrastructures, services and environment of quality to all, without any exception? Based on a conceptual approach of urban planning and on case studies in Africa and Latin America, we shall focus on 3 dimensions of a renewed urban planning: base the planning on a diagnosis of human and material reality specific to each city – involve the planning in a critical perspective of financial and human available resources – implement innovative technologies in a participatory approach including inhabitants and all urban stakeholders.