The proceedings of the Ecoparc Forum 2015 - entitled "Metropolization of Switzerland : Hindrance of Opportunity for Sustainability?" - are published as a special issue of the review TRACES. The various authors, including Emmanuel Rey, organizing committee's President, highlight the issues of the metropolization process and the objectives related to sustainability. They underline the importance of structuring the evolution of urban areas by integrating multiple dimensions. In particular, the rational use of the ground, the quality of life, the development of sustainable mobility and the energy supply are relevant. Beyond the myth of rural Switzerland, they aim to consider the Swiss plateau not as a series of separate entities but more as a large urban system to be structured and optimized.