CITI-SENSE will develop “citizens’ observatories” to empower citizens to contribute to and participate in environmental governance, to enable them to support and influence community and societal priorities and associated decision making. CITI-SENSE will develop, test, demonstrate and validate a community-based environmental monitoring and information system using innovative and novel Earth Observation applications.To achieve this, the project will: (i) raise environmental awareness in citizens, (ii) raise user participation in societal environmental decisions and (iii) provide feedback on the impact that citizens had in decisions. It will address the call’s request for effective participation by citizens in environmental stewardship, based on broad stakeholder and user involvement in support of both community and policy priorities. The project aims to learn from citizen experience and perception and enable citizenship co-participation in community decision making and co-operative planning.The concept of CITI-SENSE rests on three pillars: technological platforms for distributed monitoring; information and communication technologies; and societal involvement. Three pilot case studies will focus on a range of services related to environmental issues of societal concern: combined environmental exposure and health associated with air quality; noise and development of public spaces, and indoor air at schools. Attention will be given to representativeness of citizen participation. The case studies will be designed in collaboration with citizens’ groups and decision makers. They will be based on distributed data collection using innovative static, portable and personal devices (low-cost reliable microsensor packs) that communicate with a data repositories through mobile phones or other devices. Development of participatory methods, data management strategies, and applications to facilitate exploitation of the data and information for policy, and society, will be done.