It is likely that librarians have always to a limited degree been involved in classroom teaching. For example, it is hard to imagine that the librarians at the Great Library of Alexandria did not assemble from time to time small groups of students and visiting scholars and instruct them on the proper handling and use of the valuable scrolls that resided there. Throughout most of history librarians have been members of other professions (the clergy and scholars of various disciplines) who took on the additional duty of maintaining the library collection of their institutions. It is highly likely that these individuals introduced library concepts into their regular lectures pertaining to their area of expertise. Unfortunately, no written record appears to exist detailing how library instruction in the classroom was carried out or how often it was conducted.
German library literature records various examples of library instruction from the 17th to 19th centuries. Ewert in 1986 gave a summary of this literature and detailed where the library instruction occurred, who generally was conducting it, and what was covered. It shows that a tradition of library instruction in academic institutions had developed in Germany prior to the its origins in the United States in the late 19th century. As the United States' higher education system is based on the German model, this may have influenced the earliest academic library instruction practitioners in the US.
Melvil Dewey, the founder of the modern American library profession, articulated early on the view of the librarian as that of an educator. In the century since then, library instruction has become common practice in academic libraries. It has broadened to include instruction in information literacy and Internet searching as well. Recent leaders in the field include Larry Hardesty, Julia Nims, and Michael Lorenzen.