According with the Alps and Carpathian Conventions, the European Landscape Convention, and the Birds, and Habitats Directives the research project “Access2Mountain”, illustrated in this book, aims to promote the improvement of the accessibility in mountain areas, as a crucial factor for their social, economic and cultural sustainable development, with particular regard for tourism. In the meanwhile, it aims to enlight methods, models and tools for the containment and the reduction of negative impacts of traffic, infrastructures and tourist flows on the environment, landscape and natural-cultural heritage, particularly in the most sensitive areas of South-East Europe. The landscape vision becomes the way to approach the analysis, interpretation and design. It requires a trans-scale dimension, moving from the local level, to the environmental component, the interested context and the model region. The final output is a “system of thinking” for the decision making processes in sensitive mountain landscapes. This contribution deals with the role of a decision-support instruments, to verify the pursuit of the planned objectives, with more specific investigation regarding the following aspects: environmental effects due to the activation of plans and programmes; the degree to which the objectives of environmental sustainability indicated by current planning instruments are reached; timely identification of environmental effects that have not yet been examined; the adoption of appropriate corrective measures capable of providing indications for the possible modification of contents and actions called for in the programme; periodic communication of the results of monitoring activities to the authorities in charge of environmental matters and to the public through systematic reporting activities.