## 1 Introduction  
During the last two decades, a remarkable shift appears towards engaging the public in the decision-making processes [1; 2; 3; 4; 5; 6; 7; 8]. The goal behind the strengthening of public participation in policy making is twofold: on the one hand it serves the need for data acquisition (public opinions, views, visions, _etc._) on specific decision-making problems and the setting of goals and priorities that reflect groups involved; while on the other hand it supports the sharing of responsibilities as well as negotiating, empowering and emotional commitment [8; 9; 10; 11]. The orientation of decision makers and planners towards the engagement of public in the decision-making process can be considered as the outcome of a range of factors, with the most important being the [11]:  
* _Shift_ from \"top-down\" decision-making processes, where decisions were made by a small group of decision-making centers and technocrats [12] to \"_bottom-up_\" decision-making processes, placing emphasis on decision-making at the local level, where the protagonists are local government institutions and local communities [13];
* _Maturity_ of local communities as a result of ICTs-enabled information provision, which has placed citizens at the heart of local, but also global, problems and challenges, affecting community wealth and has opened to them new perspectives for action and engagement in the structuring of planning interventions that can lead to a visionary future, having at its core environmental protection and quality of living [14];
* Understanding that, at the local level, citizens have a good _knowledge_ not only of problems, but also of their _intensity_, which consists of important aspects for planning and prioritizing interventions that fulfill desires, values, preferences and visions of local communities, thus placing citizens as partners in the planning process [15]. At the same time, planning is in front of a number of remarkable changes and new challenges, the confrontation of which demands public engagement in the planning process. As such, can be considered the [11]:  
* Increasing _complexity_ of planning problems [16], which demands the gathering of information and knowledge from a wide range of social groups (citizens and stakeholders) in order to enrich the context and effectiveness of planning interventions;
* Increasing _intensity_ of environmental problems (climate change, heavy storms, flood incidents, _etc._) and the deep understanding by policy makers and planners that the implementation of successful planning interventions, coping with these problems, needs to focus on behavioral changes and the raising of individual and collective responsibility, thus stressing the importance of increasing public awareness as a \"tool\" that can effectively deal with contemporary environmental and other local/global challenges [17; 18]. This in turn has motivated policy makers and planners to engage public participation in the decision-making process, while at the same time has \"fired\" developments at the institutional and legislative level that have set the public at the heart of decision-making processes and institutionalized public participation in various decision problems, with emphasis on those that have certain environmental implications [19];* The need to deal with _conflicts_ appearing among various social groups, where participatory approaches can function as platforms for communication and interaction, allowing mutual understanding and thus acting as \"peace-building mechanisms\" [7, 20], with planners undertaking the role of _mediators_[8, 21, 22]. The increasing importance, attached nowadays to the role of public and stakeholders' participation in seeking for the fulfillment of sustainable development objectives and the management of the crucial environmental problems, reflects the conviction that they can, under certain conditions, constitute \"_agents of change_\" towards the desired planning direction.