Owing to ICT-enabled citizen observatories, citizens can take on new roles in environmental monitoring, decision making and co-operative planning, and environmental stewardship. And yet implementing advanced citizen observatories for data collection, knowledge exchange and interactions to support policy objectives is neither always easy nor successful, given the required commitment, trust, and data reliability concerns. Many efforts are facing problems with the uptake and sustained engagement by citizens, limited scalability, unclear long-term sustainability and limited actual impact on governance processes. Similarly, to sustain the engagement of decision makers in citizen observatories, mechanisms are required from the start of the initiative in order to have them invest in and, hence, commit to and own the entire process. In order to implement sustainable citizen observatories, these social dimensions therefore need to be soundly managed. We provide empirical evidence of how the social dimensions of citizen observatories are being addressed in the Ground Truth 2.0 project, drawing on a range of relevant social science approaches. This project combines the social dimensions of citizen observatories with enabling technologies - via a socio-technical approach - so that their customisation and deployment is tailored to the envisaged societal and economic impacts of the observatories. The projects consists of the demonstration and validation of six scaled up citizen observatories in real operational conditions both in the EU and in Africa, with a specific focus on flora and fauna as well as water availability and water quality for land and natural resources management. The demonstration cases (4 EU and 2 African) cover the full 'spectrum' of citizen-sensed data usage and citizen engagement, and therefore allow testing and validation of the socio-technical concept for citizen observatories under a range of conditions.