In the United States in recent years there has been extensive concern about school reform and keen interest in Japanese business-management practices. This paper presents findings of a case study that examined the role and responsibilities of two middle school principals, one in Japan and one in the United States. The study is based on Krug's theoretical framework (1992), which suggests a direct link between the principal's instructional leadership and school effectiveness as measured by student achievement. The paper discusses the principals' beliefs about the following five dimensions: (1) communicating the mission of the school; (2) monitoring the curriculum; (3) evaluating and supervising teachers; (4) promoting a supportive school climate; and (5) reviewing student progress. The two principals' roles and responsibilities revealed that their jobs were as different as fire and water. The American principal spent long hours evaluating teachers, monitoring the curriculum, reviewing student progress, and promoting a positive climate. He had little time to articulate the mission statement of the school. In contrast, the Japanese principal saw articulation of the school's mission as a top priority. Evaluating and hiring teachers, monitoring the curriculum, and assessing student progress were not his responsibilities. Although the two principals shared common beliefs about effective leadership, they essentially operated within two different job descriptions. The findings illustrate the importance of organizational structure and cultural expectations. The appendix contains copies of each job description. (Contains 29 references.) (LMI)