A business case for sustainability intends and realizes economic success through (and not just with) an intelligent design of voluntary environmental and social management. A business case for sustainability is different from a conventional economic business case. It can be characterized by three requirements which have to be met. Firstly, the company has to realize a voluntary or mainly voluntary activity with the intention to contribute to the solution of societal or environmental problems. These are intended activities for the society or the natural environment which are not just a reaction to legal enforcement and regulations or which would anyhow be expected for economic reasons as part of conventional business behavior. Secondly, the activity must create a positive business effect or a positive contribution to the economic success of the company which can be measured or argued for in a convincing way. Such effects can for example include cost savings, the increase of sales or competitiveness, improved profitability, customer retention or reputation. The cause and effect relationship can be direct or indirect, however, must not be speculative but rather based on a sound management argumentation. Thirdly, a clear and convincing argumentation must exist that a certain management or entrepreneurial activity has led or will lead to both the intended societal or environmental effect and the economic effect. This argumentation includes an explanation of the link between the voluntary social or environmental activity and the economic and sustainability effect. A business case for sustainability is thus characterized by creating economic success through (and not just along with) a certain environmental or social activity. In summary: A business case for sustainability results from the intelligent design of voluntary or mainly voluntary social and environmental management and creates a positive business effect based on a distinct management or entrepreneurial activity. The concept of the business case for sustainability guides researchers and practitioners alike to find answers to the crucial question: How can the competitiveness and business success of a company be improved with voluntarily created outstanding environmental and social performance?