Samuel S. Green redefined the relationship of librarians to the public in his seminal 1876 essay, Personal Relations Between Librarians and Readers. His concept of reference service, central to the public library movement, remains the foundation for the practice today (Rothstein, 1964). According to Green's vision (as redacted by David Tyckoson), a librarian:

• Instructs patrons how to use the library
• Answers patron queries
• Aids the patron in selecting resources
• Promotes the library within the community(Tyckoson, 2001, p. 186)

Librarians have performed these functions in a variety of ways, though they exist in tension with material and social constraints: library resources (Rothstein, 1964), the actual relationship of the library with the community it serves, and the skills of that community (Tyckoson, 2001). Rothstein (after James Ingersoll Wyer) characterized the main models of reference service in three main approaches: "'minimum,' 'middling,' and 'maximum'" (Rothstein, 1964, p. 39). These models, although characterized as conservative, moderate, and liberal, do not connote political schools of thought.

• The maximum, or liberal model (also known as the "Traditional Model") is closest to Green's conception of personalized service in the public library. Academic libraries have found this model to be popular also, but hard to implement on a sustained basis, requiring a large commitment of staff resources. Commercial and well–funded special libraries have more resources, and therefore are able to offer reference services using this model (Rettig, 1993).
• The minimum, or conservative model, represents the other extreme: The librarian provides some direct reference services, like ready reference, but focuses on library education to instruct clients on how to use the library themselves. Because academics and students are more familiar with their subject matter, as well as proper use of the library, it is mainly used in university and other school libraries (Rettig, 1993).
• The "middling," or moderate model incorporates practices of both the minimum and maximum models (Rettig, 1993) taking into consideration the characteristics of the library's primary clientele and its available resources to offer sustainable and useful reference services.

Many libraries have used organizational methods and technology to maximize client services with limited budgets and staff.

Tiered Reference:Initial questions are triaged by less experienced staff, who then can refer clients to librarians with more experience or specialized knowledge if their needs cannot be met at lower levels (Tyckoson, 1999).

Virtual Reference leverages technology to maximize personal and ready reference services. Degrees of human intermediation and response time vary. Wide varieties of ICTs, from the telephone to Internet services, have been tried over the past 20 years. Internet technologies such as email, live chat, co—browsing and screen sharing show promise, as do some automated systems in limited contexts (Tyckoson, 1999).

Appointment based and Premium Service. Some libraries require clients to set appointments (Tyckoson, 1999), or charge a fee for personal service (Rettig, 1993).

Though the maximum model‚—one–on–one personal service — is still central the practice of reference service, it can place unsustainable strains on library resources (Tyckoson, 1999).

For Further Reading:

• "Reference Service" entry in the World Encyclopedia of Library and Information Services
• "What is the Best Model of Reference Service?" by David Tyckoson.
• "What's Right With Reference," by David Tyckoson.
• "On the Desirableness of Personal Relations Between Librarians and Readers: The Past and Future of Reference Service," by David Tyckoson.
• "An Ideological Analysis of Digital Reference Service Models," by Juris Dilevko.

Bibliography (APA 5th)

Rettig, J. R. (1993) Reference service. In World encyclopedia of library and information services(3rd ed.) Chicago: American Library Association.

Rothstein, S. (1964). Reference service: the new dimension in librarianship. In A. R. Rowland (Ed.), Reference services (pp. 35-46). Hamden, Conn.: Shoe String Press.

Tyckoson, D. A. (1999). What's right with reference. American Libraries, 30(5), 57-64.

Tyckoson, D. A. (2001). What is the best model of reference service? Library Trends, 50(2), 183-196.

Ward Smith