The vast and growing array of concepts, methods and tools in the sustainability field imply a need for a structuring and coordinating framework, including a unifying and operational definition of sustainability. One attempt at such framework began over 25 years ago and is now widely known as the Framework for Strategic Sustainable Development. However, as with the larger sustainability field, the social dimension of this framework has been found to not be sufficiently science-based and operational and thus in need of further development. In this two-part series an attempt at a science-based, operational definition of social sustainability is presented. In part 1 a systems-based approach to the social system was presented, based on extensive literature studies as well as conceptual modelling sessions using the Framework for Strategic Sustainable Development as the guiding structure. The focus of that study was on the essential aspects of the social system that need to be sustained, namely trust, common meaning, diversity, capacity for learning and capacity for self-organization. The aim of this second paper is to identify and present overriding mechanisms by which these aspects of the social system can be degraded, thereby finding exclusion criteria for re-design for sustainability. Further literature studies, conceptual modelling sessions and initial testing of this prototype with partners in academia, business and NGOs were performed. Based on the understanding of the essential aspects of the social system and the identified overriding mechanisms of degradation of these, a hypothesis for a definition of social sustainability by basic principles is presented. The proposed principles are that in a socially sustainable society, people are not subject to structural obstacles to: (1) health, (2) influence, (3) competence, (4) impartiality and (5) meaning-making. Overall, the two papers aim to provide a hypothesis for a definition of social sustainability, which is general enough to be applied irrespective of spatial and temporal constraints, but concrete enough to guide decision-making and monitoring. It is also a further development of the social dimension of the FSSD, which practitioners and researchers have requested for some time and can act as a support towards better integration of social sustainability in many other fields, e.g., sustainable product innovation, sustainable supply chain management, sustainable transport system development, and others.