This paper presents findings of case studies that applied social exchange theory to examine the instructional leadership roles of four exemplary high school department chairs. Data were gathered at four suburban high schools in a large metropolitan area of the midwestern United States using the methods of observation and interviews with the chairs, teachers, administrators, and other building chairs. Findings indicate that the chairs engaged in similar leadership practices as middle managers within their different high school environments. The chairs maintained constant communication with administrators and teachers, delivered services and rewards, practiced collegiality, and treated teachers and administrators with respect, fairness, and sensitivity. Finally, by skillfully utilizing the exchange process, chairs acquired considerable informal authority that they used to carry out their tasks. Five tables and one figure are included. (Contains 52 references.) (LMI)