Background Some 1 661 692 tonnes of municipal waste was generated in the Barcelona metropolitan area in 2007 (an average of 1.46 kg/inhabitant/day. Selective collection accounted for around 31% of the generated waste, while around 52% of the generated waste was treated through selective collection and treatment plants. After the finalisation of the revision of the European Union Waste Framework Directive in 2008, these figures need to be improved with the participation of, among others, citizens. When surveyed on the main environmental problems facing them, citizens usually only mention waste in the context of civic problems and street cleaning. Most citizens are unaware of the volume of waste they produce or how it is treated. This lack of awareness, together with the circulation of urban legends about recycling, is a hindrance to citizens’ involvement and leads to a poor household waste separation rate. Objectives The project aimed to promote understanding of the concept of the 'European recycling society' in Barcelona. This awareness-raising effort also supports the objectives of Barcelona's Metropolitan Programme of Municipal Waste Management (PMGRM) 2009/2016. This hierarchical and sequential application includes the following principles: reduction of waste generated by prevention and reuse; achievement of the maximum material use of waste resources by improving collection systems; evaluation the remaining fraction with a view to material recovery; and demonstrating the importance of citizens’ involvement. Results The COR project showed citizens that their involvement was essential if the waste they generate is to be reduced and efficiently recycled. They were encouraged to apply the best practices in waste management (separation of waste and good use of collection systems), until such habits become part of a daily routine. The project’s awareness-raising was considered crucial in tackling the lack of knowledge about the amount of waste a person generates, where it goes, what is done with it, and products that can be made from it. The quantitative goals of the project were those set by Barcelona’s PMGRM, which were in turn based on those in the Waste Framework Directive (WFD): to increase the amount of waste sorted and the amount being treated. The project increased the percentage of selected waste being collection from around 31% to 36% (the goal was 40%), and increased the percentage of waste treated before it goes to landfill from around 52% to 66% (the target was 90%). The project helped reduce the total amount of waste generated, from 1.46 to 1.29 kg/inhabitant/day. The project’s awareness-raising campaign was mainly targeted at adults under 35, a population segment that is well-informed about waste but, as the surveys showed, is unwilling to implement this knowledge in their daily lives. Taking into account that the target group is the main user of social networks, the project’s main activity was a 2.0 communication campaign based on digital and viral marketing. This was the first time that such an innovation viral marketing campaign had been used by a public authority in this field. It took shape in the form of ‘Moviment R’ (R Movement) on social media networks, viral marketing and street marketing actions. This series of activities reached more than 7.5 million people, far above the original 500 000 targeted. Moreover, there were many other initiatives arising as a result of the synergies created by the project. COR also involved traditional actions, such as actual tours of waste management plants, training activities, talks, workshops and seminars. A total of 12 719 people took part in these actions, which also included audio-visual presentations, virtual tours of waste treatment plants, and the publication of children’s stories. Moreover, the project developed activities to compare methodologies and results, including meetings with stakeholders, and tools to assess the level of goal attainment, such as the analysis of yearly data on waste. The project helped encourage citizens to change their habits and to include recommended domestic waste management (separation and selective collection of the different fractions) in their daily routine. This was thanks to the project activities, but also to the social/economic context that has improved the recycling system generally in the Barcelona area. The data gathered by the project showed that the trend has been toward a reduction in wastes produced, an increase in selective collection, and a large reduction in the quantity of waste being sent to landfill. The main environmental objective of the project was to implement the WFD. Specifically, the goal was to demonstrate to people that their involvement is essential if the objectives of the WFD are to be achieved. In addition, it has contributed to meeting other national and European environmental policy objectives. By reducing the amount of waste sent to landfill some of these sites can be closed, while recycled waste can be transformed into a range of products and compost. Waste can also be directed into energy production. Several areas involving improved waste management have the potential for mitigating the impacts of climate change. Further information on the project can be found in the project's layman report and After-LIFE Communication Plan (see "Read more" section).