In this study we explored how the science department shaped the relationship between a science department head, Mr Greg, and a teacher, Ms Horton, as they grappled with their expectations of, and responsibilities for, teaching and leadership in the daily life in the department. We found that, from their life histories and their positions in the department, Mr Greg and Ms Horton have developed different values and visions that shape the ways they construct their work, particularly in relation to the place of subject matter, goals for students, teamwork, roles and responsibilities and accountability. Although both shared a commitment to their students and to their subject, Mr Greg saw his contribution in subject organizational terms and Ms Horton saw hers in personal student terms. Orderliness and stability were important to the department head whereas Ms Horton valued spontaneity and innovation. Collaboration was Mr Greg's method of achieving the business of the department; working alone allowed Ms Horton the freedom and flexibility she needed. Accountability for Mr Greg was framed in organizational terms; Ms Horton was more concerned with the learning that took place in her classroom. Our case study looks at the range and intensity of the forces shaping the work of teachers and the way they organize themselves at work. We argue that, if we wish to continue to improve teaching and learning, particularly in secondary schools, we need to know a great deal more about the forces that operate in subject departments.