The “TRAIL” initiative, proposed by the Italian, Chilean and French networks, is conceived to further develop the intersections of the fields of science communication and citizens’ science. The main motivation is the need to communicate and share with a wider audience the existence, aims and activities of the LTER networks. This will increase the socio-ecological impact of LTER studies and their interactions with the civil society. TRAIL aims at creating a real movement of researchers and citizens, by planning and implementing trails connecting LTER sites in order to: i) promote LTER networks and LTER activities involving non-expert audiences, ii) involve citizens in the research carried on at the LTER sites, through the launch of citizens’ science (CS) initiatives, iii) contribute to the increase of the ecological awareness and literacy, and iv) integrate local and international scales of ecological phenomena and LTER networks. The main purposes of the initiative are: 1) to improve the spreading of knowledge of local environments and of the on-going LTER activities through direct experience; 2) to start gathering and submitting scientific data by a large number of volunteers; 3) to integrate local data with global scale ones through networks of LTER sites; 4) to encourage inter-continental collaborations among Northern and Southern Hemisphere researchers and communities. The appropriate scientific questions, that will aggregate citizens, LTER scientists, and stakeholders, will be discussed and defined within each national network and LTER site involved in the initiative. One of the first, common elements is the high mountain biodiversity of the European Alps and Apennines, and the high latitude ecosystems of Cape Horn in South America. TRAIL aims at stimulating CS within the I-LTER network, meaning in different cultural, economic, scientific and political contexts. This provides a unique opportunity to examine various facets of CS in different geographical contexts.