The project "Youth commited on both sides of the Mediterranean : youth, science and democracy in Tunis and Ile-de-France" involves about 15 French and 15 Tunisian youngsters and focuses on the challenges of the social and ecological transition (climate change, energy, biodiversity, water ...). The project is organized around two main meeting moments, 12 days in Tunisia, and then, 10 days in France. This project has been designed as a tool for empowerment and initiative for the yound participants, and started as early as July 2014, with the support of the Ile-de-France regional council. Following a first exchange session in France in august 2014, involving young Tunisians, and the participation of all involved youngsters in the World Forum for Science and Democracy in March 2015, in Tunis, the project goes on in 2015, with the international climate dialogue agenda as a focus point (COP21). The project introduced here therefore includes a co-training and job-shadowing exchange in Tunisia, as imagined and designed by the young participants, and a youth exchange in France, during the COP21. The project "Youth commited on both sides of the Mediterranean" was intended to use these international events as mobilization spaces, critical thinking experiences, and places where the youngsters can connect their own local challenges with more global issues. It is the project's key principle that such events should be part of a longer term exchange process, so that sustainable relationships and cooperations can be developed between the yound participants, and between their respective territories. Moreover, this project was designed for the empowerment, autonomy and capacity building of the younger generation, on the topic of climate change and ecological transition in particular. It will provide tools for the youngsters to be able to largely share the challenges and topics involves with a broader audience, and be active members of their home society as well as the global community.