Schools are considered as important settings for health education and the promotion of functioning, healthy people. Health-promoting schools (HPS) take a holistic approach to health promotion that addresses all school levels and members of the school community. Although it is assumed that school leaders are crucial in the implementation of HPS, little is known so far about which specific factors are relevant. The purpose of this study was to analyze the role of school leaders’ attitudes, health literacy, and health status in HPS implementation. An online survey was conducted in June 2021, and the final sample consisted of N = 358 school leaders. Regression and moderation analyses were conducted to answer the research questions. The results showed the relevance of health literacy and attitudes toward HPS for the implementation of HPS. By contrast, only some aspects of health status are relevant. Attitudes toward HPS moderate the effect of health literacy on HPS implementation, with positive attitudes toward HPS amplifying the effect. Implications for practice and future research are discussed.