This paper examines three concepts relating to the role of heads of department (HoDs) in secondary schools: boundary management; the roles of subject leadership and departmental functioning as HoD activities; and the place of HoDs in evolving school hierarchies. To throw light on the last an empirical study is reported that explores hierarchies in middle management across three professions, and draws comparisons. The paper rejects boundary management as an appropriate model. It concludes that hierarchical models in education are very different from those in the military or in business and establishes a typology against which to view the research data. (Contains 1 table.)