Like other institutions, libraries are methodically arranged for efficiency and customer service. Depending on the size of the collection and budget, the organizational structure of a library will be led by a single director or a director and a few assistant directors. These typically tenured library science professionals then supervise a line of departmental managers — some responsible for a particular collection or research function, others dedicated to more administrative tasks. All other library employees fall under the supervision of these middle managers.
A director is technically the top of the organizational structure of a library, even though it is customary for this director to answer to a library board of trustees. This body's members are often appointed by elected county commissioners, or in some communities by the voters. For libraries attached to educational institutions, the school's board of directors will appoint library trustees for specified terms. The background of these trustees can vary widely, from business leaders, lawyers and up-and-coming politicians to retired citizens, die-hard library supporters and educational leaders.
The board usually oversees the budget, but it is the director who oversees the day-to-day spending of that money to further the library's mission. Immediately under the director and any assistant director the library can afford are a group of managers. Some are responsible for staff and acquisition budgets dedicated to certain collections — like the Non-Fiction, Classics or Reference departments, or certain functions — like a Youth Programs or Adult Education. An operations manager may run a department of sub-managers performing tasks like accounting, marketing and information technology (IT).
Large libraries with extensive collections and generous funding are likely to have more managers with more specialized functions. A small township library may have just a director and a handful of volunteers who split the library's many duties in whatever way works best. Other duties or departments for which a manager is often assigned in larger libraries include, circulation, Web, library extension services, branch supervision, children, seniors, community, research and after-school.
In all but the smaller libraries with mostly volunteer staff, departmental leaders are positioned in the organizational structure of a library to supervise entry-level librarians, student employees and volunteer staff. A circulations manager may oversee a small army of library students or volunteers, each with the responsibility of keeping organized and up-to-date on a particular part of the collection. For instance, in the organizational structure of a library the size of the University of Chicago's, a collections manager oversees staffers responsible for Fiction, Non-Fiction, History, etc.. A library of lesser means, of course, may have a collections manager responsible for each of the library's acquisitions.