(1) Background: Health literacy is considered a personal asset, important for meeting health-related challenges of the 21st century. Measures for assisting students' health literacy development and improving health outcomes can be implemented in the school setting. First, this is achieved by providing students with learning opportunities to foster their personal health literacy, thus supporting behavior change. Second, it is achieved by measures at the organizational level promoting social change within the proximal and distal environment and supporting the school in becoming more health-literate. The latter approach is rooted in the concept of organizational health literacy, which comprises a settings-based approach aiming at changing organizational conditions to enhance health literacy of relevant stakeholders. The HeLit-Schools project aims to develop the concept of health-literate schools, describing aspects that need to be addressed for a school to become a health-literate organization. (2) Method: The concept development builds on existing concepts of organizational health literacy and its adaptation to the school setting. (3) Results: The adaptation results in the HeLit-Schools concept describing a health-literate school with eight standards. Each standard depicts an area within the school organization that can be developed for fostering health literacy of school-related persons. (4) Conclusions: The HeLit-Schools concept offers an approach to organizational development for sustainably strengthening health literacy.