Schools have become too complex organisations to be led by a single person (a headteacher), or a small team of their associates, since the demands placed on schools, especially on school leaders, are continually increasing. The need to involve other stakeholders next to the headteacher (such as teachers and other staff members, students and their parents, as well as representatives of the local community and external stakeholders) in the decision making process is becoming more and more emphasized. Given that school leadership is increasingly associated with school efficiency and student achievement, there is a growing interest in school leadership models that involve not only the headteacher but also other stakeholders in leadership activities. The theoretical part of the paper explores the specifics of the profession of a headteacher in a primary school and provides an overview of research on school leadership models. The emphasis is on delegating and distributed leadership. Due to the fact that school leadership model is directly linked to the way decisions are made in a school, it is examined in detail who and how takes part in the decision making process; what is their impact in the process; and what kind of social relations it involves. Distributed leadership is increasingly being researched as a leadership model that contributes to greater school efficiency and yet it is often understood as delegating. Hence, a study was conducted to determine whether primary school principals in the Republic of Croatia predominantly apply a delegating model or distributed school leadership in their work. The research was conducted using an online questionnaire, and a representative sample of primary school principals from the entire Republic of Croatia participated in the research. In addition to investigating the frequency of the applied models of school leadership, the headteachers’ demographic features and school characteristics were also looked into in regard to the applied leadership model. The results of the research indicate that headteachers of primary schools in the Republic of Croatia more frequently use delegating in their work than distributed school leadership.