This examination of the concept of leadership in the context of a large science-engineering library focuses on the importance of communication as it explores relevant social and political factors from an administrative perspective. The paper begins with an overview of the services and collections of the science-engineering library. The nature of leadership, including the importance of vision and communication, is then considered. A discussion of the environment of the science-engineering library--academic departments, students, other library administrators, and professional associations--follows. Categories of leadership roles of the administrator of the major science-engineering library are outlined: interpersonal roles (figurehead, leader, and liaison); informational roles (monitor, disseminator, and spokesman); and decisional roles (entrepreneur, disturbance handler, resource allocator, and negotiator). It is concluded that, although the major science-engineering library is unique, it is a microcosm of the main library, and the basic administrative skills needed to administer primary activities and operations are similar for the directors of both libraries. (4 references) (MES)