Higly glazed facades has been increasing with the intention of more daylight gain in buildings. However, more daylight may not always bring more satisfaction considering many factors that influence daylighting quality. Uncontrolled daylight brings visual and thermal problems which end up with negative interactions with user comfort. Library spaces in which different task activities are performed simultaneously need to be well designed in terms of daylight performance, thus the user satisfaction could enhance. This thesis particularly focuses on the optimization of visual performance in an academic library with a new layout arrangement and a light shelf-reflective louver system. One of the reading rooms of Izmir Institute of Technology Library was chosen as a reference case, where the instrumental monitoring of existing daylighting conditions was performed. The reference case was then analyzed with daylight simulation tool, so that the outcomes would later be used for the performance testing of the new proposals. Luminance patterns and illuminance distribution of different points were evaluated in terms of visual performance recommendations. A new layout arrangement and light shelf-reflective louver system were proposed respectively in accordance with the deficiencies of simulation results. Ultimately, daylight performance of the library was significantly improved regarding illuminance and luminance based distribution. Despite a diminution in average illuminance due to the dramatic decrease of excessive amount of daylight near the window, the big picture gives the clues on how a simple layout change and a daylighting system can make enhancement on the visual performance of a library reading room.