"Our project ""Creating a Sustainable Tomorrow"" aimed at raising students' awareness regarding their consumer behaviour and the ecological problems it entails. We focussed on various environmental problem areas and tried to develop an understanding that a more sustainable lifestyle is needed if we want to save the planet. Students had the chance to learn about their own surroundings, to experience other European realities and to develop an understanding that ecological problems, while being regionally diverse, are universal and concern all of us. The desired outcome of the project was to make the students actively change their consumer behaviour (at least a bit), to disseminate the need for change, and to thus make a difference as young European citizens.The 4 schools involved in this project were very different regarding their social, geographical and ecological conditions - a circumstance that we exploited for the learning/teaching activities. The Spanish school is a medium-sized urban secondary school with a wide spectrum of social backgrounds, located close to the center of Madrid and at the same time close to the biggest shanty town in Europe, where waste is a big problem (topic: ""consumer behaviour and waste""). The French school, a small collège, is located in Anglet, in a semi-urban area in close proximity to the ocean (topic: ""(virtual) water""). Since Norway is rich in oil but uses mostly water power and has a leading role in environmental care, we dealt with the topic ""energy"" at the school in Trondheim, a very modern junior high school with state-of-the-art equipment and a rather different school system. The German school in Groß-Umstadt is a rurally located grammar school, which suggested dealing with agriculture and bio-diversity at the last meeting. The project was subdivided into different phases. In the 1st semester we examined, evaluated and compared our consumer behaviour and examined the ecological consequences of our wasteful lifestyle. We gained awareness that a more sustainable and considerate lifestyle is needed. In the 2nd semester, we explored our communities/regions and found out what is already being done in terms of a sustainable development, before we researched new ideas and inventions to find out what else could be done to be more sustainable in the 3rd semester. In the first 3 semesters, we produced e.g. presentations, podcasts, articles and films in English on all the above topics, which we presented at our schools, at the country meetings and/or shared on the TwinSpace. In the 3rd / 4th semester the students wrote stories about their visions of the future (story competition), which were the basis for films on ""Life in the Future"" (film competition). During the country meetings the students worked in-depth and in international teams on an ecologically relevant topic (e.g. waste, water, energy, food). In international work groups, they produced “tangible” results, using different methods of cooperative and task-based learning. Eventually, the sum of all the theoretical and practical project work resulted in a ""Charter for a Sustainable Lifestyle”. (For some of our results see: www.cast-erasmus.com)By participating in the project, the students acquired and/or developed important key competences and transversal skills relevant for their future careers: they expanded their foreign language skills, digital skills, presentation skills as well as their basic competence in science, geography, social studies and technology. In addition to that they also developed their ability to think critically, taking a step further on their way to becoming more involved European citizens.For the teachers, the project provided the opportunity to get to know different school systems and innovative teaching methods as well as to reflect on and improve their own teaching style. Teachers at each school worked more closely together in interdisciplinary teams and thus enhanced the cooperation and team spirit among colleagues.Project results such as multilingual glossaries, the presentations on ecological problems, the “Charter for a Sustainable Lifestyle"", the evaluation material for the story/film competition etc. can be used for class work at all schools beyond the duration of the project. Other potential longer term benefits might be an increase in transversal skills and competences, individual changes in consumer behaviour patterns and the possibility that some sustainable ideas might be implemented in the participants‘ families and/or communities in the future."