We define sustainability from a value chain perspective, which we term ‘value system sustainability.' Value system sustainability emphasizes firm's effort to make decisions in a way to be sustainable not just from the firm's own perspective, but from the perspectives of the entire value chain participants including internal stakeholders like managers and employees and external stakeholders like suppliers, vendors, distributors, customers, communities, governments, non-governmental organizations, and even those in other countries, i.e., in the global market. In a sense, it looks into the sustainability issue in a holistic view, and therefore is sublimated to a highly comprehensive level. Sustainable action or behavior means that value is created in such a way that the output is more valuable than the input so that the surplus, i.e., output minus input, can be preserved for future value creation. Here the concept of value is not just monetary, but encompasses various tangible and intangible elements. We develop a framework to define and assess firm's corporate sustainability, i.e., value system sustainability. It consists of three dimensions. First, there are three areas of sustainability, i.e., economic, social, and natural (environmental). Second, there are stakeholders, for whom the firm should pursue sustainability, i.e., the firm's effort for sustainability must be assessed not only by the firm's own internal perspective, but also by the external stakeholders'. Finally, the level of sustainability should be measured. Our model uses seven levels determined by strategic and operational priorities: ignorant, passive, reactive, receptive, constructive, proactive, and finally transcendental. After we explain our framework, we present an example to show how to utilize it in the real company. We conclude our paper by blueprinting the future research
