The study aims to investigate the level of Information Service Quality at SQU Main Library, acting upon students' opinions using the LibQUAL+ model as a standardized instrument to identify the gap between the perceived and expected levels of service quality. The work has adopted a quantitative approach using LibQUAL+ Questionnaire Survey as a tool to gather data, The survey divided into three dimensions related to Library Service Quality: Affect of Service, Information Control and Library as Place. A fourth dimension dealing with User Satisfaction has been added and considered by this study. The sample is composed of 1,023 Male and Female students, randomly selected which represents approximately 6% of the study community. The research study has led to major findings: One of the key results shows that the average of Achievement Gap is negative (-0.66(, implying that, generally speaking, the Information Service Quality at the Main Library doesn't match the users' desire and expectations. The reached findings also indicate that the users' perception of the provided Information Service Quality is quite high (7.06). Furthermore, the results reveal a high-level of user satisfaction with the provided information service among the study sample (7.29), indicating a moderate positive relationship between the quality dimensions and the general satisfaction with the provided services. Finally, the study recommends the necessity to work on the narrowing of the gap between students' perceptions and expectations. The library should find ways to better serve and respond to its users' expectations, enhance the service quality requirements, review the level of provided services and set up strategic plans in order to increase the use of its sources, facilities and services. The study also suggests the establishment of quality Unit reporting directly to the Director's Office, which will be responsible for quality control, performance assessment and awareness raising within the library