Sustainability represents a ‘grand challenge’, which can often not be addressed by actions of individuals or single organizations alone. To understand collaborative sustainability activities, in this article we propose the concept of open sustainability. We derive open sustainability from literature in the areas of sustainability, open approaches, and open innovation, and define the concept based on key tenets as follow: open sustainability refers to an orchestrated distributed process in which a focal company interacts with partners across organizational boundaries in order to better achieve its own (micro-level) sustainability objectives, its direct nets' (meso-level) sustainability objectives, and the broader networks' (macro-level) sustainability objectives, both short and long term. Based on this definition, we introduce the articles of our special section on open sustainability.