This paper examines the changes in school principals' role expectations in the beginning and developing process of shared decision-making in school management in the United States. My analysis considers School-Based Management (SBM) policies and principalship between the 1970s and 1990s in Florida. Although SBM was initiated in the 1970s, it was not established successfully. According to some analyses, one of the main factors in this failure was that principals and teachers did not understand the necessity of their own role changes. In the 1980s, reform policies were implemented to define principals as school managers, and the Florida Principal Competencies (FPC), a criterion to describe the competencies school principals should demonstrate, was developed in 1983. However, the FPC seemed to disregard shared decision-making. In the 1990s, a new SBM policy clarified the specific responsibilities of the State, the district, and the school. The FPC was also revised in 1994, and it reflected some important changes in the principal's role expectations in terms of shared decision-making. For example, it redefined the parent as a participant in the decision-making process. My analysis demonstrates that the revised FPC emphasized that the school principal is expected to build and facilitate the process of multi-way communication among the stakeholders by using specific data. Such communication is seen to promote the success of shared decision-making procedures by school advisory councils. Thus, it was found that the role expectations of principals changed in the 1990s. In addition, it is important to note that views regarding school organization have changed. Until the 1980s, school management had been viewed as a one-way, top-down process placing the greatest emphasis on the principal's values. However, by the 1990s, school management had progressed to a horizontal and multi-way relationship among diverse stakeholders, with the principal being seen as just one of the members.