In an article posted on the new OECD blog on development, "Development Matters", UN-Habitat Executive Director Joan Clos explains why the challenges of the 21st century require a new concept of urbanisation in Africa. According to him, urbanisation is an unprecedented opportunity for developing countries, which will account for 95% of urban growth between now and 2050. By that date, the number of urban dwellers living in African cities will have quadrupled. To prepare for the social, economic and environmental implications of such a transformation, African countries need to renew their concept of urbanisation in search of a model adapted to the challenges of the 21st century. For now, they remain attached to that of the last century, characterised by the dominance of automobile transport, limited public spaces and urban sprawl, as in Accra, where only 17% of urban space is devoted to streets and boulevards. This configuration creates problems of environmental degradation, land use, safety and social exclusion. In fact, 60% to 70% of the inhabitants of African cities live in slums, without access to basic public services. If African cities do not facilitate intra-city movement and do not improve their connections with rural areas, their urbanisation will not support the economic opportunities urbanisation has created elsewhere. One of the keys for their transformation is to provide municipalities with the resources to take charge of urban planning and ensure that growth is distributed equitably among populations. The New Urban Agenda, which will be adopted in October at the UN Habitat III conference, marks a paradigm shift in the conception of urbanisation – not as a threat but as a means of shaping sustainable, equitable and prosperous societies.