This study develops three alternative models of acade- mic library Web site usage based on the Technology Acceptance Model (TAM). The three alternative models depict relationships among various intrinsic and extrin- sic determinant factors of an academic library’s Web site usage. The four factors included in the models are per- ceived ease-of-use, perceived usefulness, service func- tionality, and task functionality. These four factors are hypothesized to affect directly or indirectly both factors of satisfaction and intention-to-use. LISREL analysis using survey data shows that the best-fit model is the “Dual Mediation Impact” Model. Research and managerial impli- cations for the academic library are discussed. Future re- search directions and limitations also are provided. Introduction Information technology (IT) is radically changing the face of academic libraries, their organizational structures, and the manner in which they deliver services to their users. Since academic libraries are being asked to provide greater services with less resources, they are implementing use of Web-based services (Jankowska, 2004). These new services and features are influencing the perception of the user’s overall evaluation of academic libraries. Traditionally, the evaluation of acade- mic libraries was performed primarily by assessing the extent of the physical library use and the user satisfaction with the academic library’s printed collection (Cotta-Schonberg & Line, 1994; Nicholson, 2004). With the increased use of Web- based services and features, the overall evaluation of the aca- demic library must now include not only the use of the physical facility and printed collection but also online usage and electronic resources (Shi & Levy, 2005). Recent efforts to assess library use and user satisfaction have involved the use of the LibQUAL+ instrument. The LibQUAL+ instru- ment includes various measures related to the use of elec- tronic access to materials, Web site usage, and electronic information access tools (Cook, Heath, Thompson, & Thompson, 2001; Heinrichs, Sharkey, & Lim, 2005). Previous research including LibQUAL+ studies put little emphasis on the relative importance and role played by library Web sites and their antecedents. Although there has been in- creased attention in understanding the value and mechanism of Web-based library services and electronic resources, more re- search is needed to assess their impact on the evaluation of aca- demic libraries. Previous research in the information services and the e-business field has assessed motivational factors asso- ciated with information-seeking behavior (Weiler, 2005), Web site usage (Mack, Manoff, Miller, & Smith, 2004), task func- tionality (Teo, 2001), and service functionality (Collier & Bi- enstock, 2006; Kelley & Orr, 2003). In addition, research studies have focused on the individual’s motivational factors, other determining factors of the Internet (Teo, Lim, & Lai, 1999), and/or general success factors of Web sites (Liu & Arnett, 2000; Wulf, Schillewaert, & Muylle, 2006). Well es- tablished in the literature is the fact that an individual’s behav- ior is determined by both intrinsic and extrinsic motivational factors (Atkinson & Kydd, 1997). The intrinsic motivation fo- cuses on the person’s inherent satisfaction from an activity for the sole reason of performing the activity or task. The extrinsic motivation focuses on the person’s achievement of a defined goal or objective; the performance of the activity or task is such that the completion in achieving the defined outcomes is dis- tinct from the task or activity (Atkinson & Kydd, 1997; Davis, Bagozzi, & Warshaw, 1992; Venkatesh, 1999). The pioneering work of Davis (1986, 1989) initiated a new stream of research that investigates the determining factors of IT, including the use of the Internet and library Web sites. He assessed the determining factors of IT adoption and JOURNAL OF THE AMERICAN SOCIETY FOR INFORMATION SCIENCE AND TECHNOLOGY, 58(14):2325–2334, 2007 Determining Factors of Academic Library Web Site Usage John H. Heinrichs Wayne State University, 106 Kresge Library, Detroit, MI 48202. E-mail: ai2824@wayne.edu Kee-Sook Lim, Jeen-Su Lim University of Toledo, 2801 W. Bancroft, Toledo, OH 43606. E-mail: {klim2, jlim}@utnet.utoledo.edu Melissa Allen Spangenberg Wayne State University, 106 Kresge Library, Detroit, MI 48202. E-mail: at5115@gmail.com Received July 5, 2006; revised January 22, 2007, June 25, 2007; accepted June 25, 2007 © 2007 Wiley Periodicals, Inc. • Published online 26 October 2007 in Wiley InterScience (www.interscience.wiley.com). DOI: 10.1002/asi.20710