This chapter wraps up the presented information and emphasizes pivotal findings, proposed suggestions and conclusions. Sustainability is an inherent aspect of Western civilization, is deeply embedded in European history and culture, is an integral part of our life and a key factor for the future. Sustainability was shaped by its spontaneous evolution and closely linked to social and economic developments. The research aim of this monograph is to achieve a deeper and contextual understanding of the concept of sustainability and its framework was projected in two mutually related questions: (i) what is the foundation, development and meaning of the concept of sustainability in Europe and (ii) what kind of regime and duties has it involved in Europe? Based on a developed presentation of the methodology, the terminology and scientific background, the chronological critical analysis revealed the transformation of sustainability from a rather narrow accountability command of leaders in local settings into a strong multi-spectral and multi-sectorial supra-regional call for the responsibility of all subjects. This is reflected by a legal regime which progressively regulates its formal aspects (reporting), even partially its content aspects, and expands the pool of subjects to be induced to embrace such a newly emerging liability.