A quasi-experimental study conducted in Ames Public Library, Ames, Iowa was used to evaluate whether lighting would be the main element influencing library users' choice of study space, or the greater influence could be the need for personal privacy. The study had 15 study carrel seats; each study carrel had a small built-in bookshelf and side dividers to provide an individual user space. The experiment was composed of two parts: the first part (the control setting) was conducted under existing library lighting conditions, and the second part (the test setting) incorporated four additional desk light fixtures into the space. The survey questionnaire and observations were distributed and conducted for investigating the possible changes in seating pattern related to the additional light fixtures. Cross-tabs, chi-square, independent-sample T-Test, and one-way ANOVA in SPSS statistical program (version 11.0) were used to investigate five research questions which examine the major hypothesis of this study "does lighting significantly affect choice of study space." The result supported the hypothesis and suggested lighting does not only provide library users the visual illuminations to check out books, and also it is an important element for determining the functional and efficient work surface that would influence users' choice on where they like to work. Even though 70 to 80 percent of library users and the building standard codes suggests the light is bright enough in general, the placement of the additional task light fixtures will be another helpful tool to create a more aesthetically pleasing and comfortable reading space for all library users.