There is a paradigm shift in progress in reference collections affecting the content, format, and use of reference materials. This shift is a result of changing formats for reference products, and it presents challenges to traditional reference services. In order to better understand where reference collections are heading, we must take a look back to see how we got here. This chapter defines a reference paradigm, looks at the history of reference in libraries, and examines the shift from both a reference library product and reference service perspective. It also describes how major changes have impacted traditional reference titles and how libraries and users have adjusted to those changes.
