The paper analyzes trends in ILL activity in US academic and research libraries over the past two decades. ILL activity has increased over this period, primarily due to growing requests for returnable items (e.g., books, audiovisual items, microfilms) as opposed to non-returnables (e.g., copies of journal articles, conference papers). The author finds that ILL transactions have increased due to several factors, including a growth in Web-based discovery tools as well as efforts by libraries to simplify the ILL process and improve delivery options, thus decreasing the turn-around time for requests. Additionally, many research and academic libraries have been hard-pressed to maintain adequate collections budgets in the face of skyrocketing prices, so they must rely more on ILL for little-used materials.

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