In this paper, we contrast the perceptions of sustainability of for-profit and non-profit organizations (NPOs) to show a difference in perception and understanding. A two-study design helps us to decisively examine the existing differences. Using a content analysis based on textual publications of both types of companies, we identify relevant topics related to sustainability, which we assign to the triple bottom line dimensions (social, environmental, and economical) as well as to the Sustainable Development Goals. Accordingly, NPOs focus primarily on environmental issues, while for-profit issues often report on social issues. To substantiate this difference, we conducted interviews with decision makers from the NPO environment. Analysis of the interviews reveals a divergent picture. Based on the results of both studies, we derive a model that depicts the process of NPOs to develop sustainability strategies and their influence on long-term sustainability on an organizational and global level. Our research highlights the important role of NPOs in the context of facing grand challenges and contributes to the research on sustainable business development, sustainability reporting and sustainable finance.