In spite of improving the library performance (LP) of academic libraries (ALs) is based on a set of standards and criteria, improving the SPALs is relied on the vision of the ALs’ decision-makers; and subjected by a number of barriers that hinder improvement. This research aims to improve the LP of the Arab International University (AIU) in Syria. The focus is made to achieve improvement based on the end-users’ expectations and requirements (EUERs). Thus, identifying the EUERs is aimed in this research also. Data was collected by adopting a mixed methods approach, embraced to a single case study (LAIU). Primary quantitative data was collected by distributing two questionnaires to the end-users (undergraduates & academics). A printed-format questionnaire was designed for the undergraduates, while the academics’ questionnaire was designed using Smart-survey. The aim of these questionnaires was to understand the end-users’ perspectives, expectations, and their requirements of the LAIU. 11 semi-structured interviews were conducted with 8 librarians and 3 administrators to identify the situation of the LAIU, and understand the library staffs’ perspectives about the EUERs and end-users’ ISB. SOWT analysis was used to address the strengths, weakness, and threats facing the library, and their suggestions to improve the LP. Furthermore, the analysis of the secondary statistics collected from the LAIU and related websites took place in this study to support the primary data collected. A total of 228 undergraduates, and 30 academics have participated in this study. The data collected from the questionnaires were analysed using PASW software; version 18.0, while the collected data of the interviews was analysed thematically using NVivo 10.0 software. To maximise the outputs of the research and understand the holistic situation of the LAIU, the tools of the SSM were implemented. This assists in identifying the problematic areas of the situation. A number of challenges and barriers have been discovered relating to four categories: EUERs, end-users’ information-seeking behaviour, end-users’ satisfaction, and the LP. The analysis showed that although the EUERs are academic in the first place, there are differences regarding their demographic variables. It presented that end-users are not strongly satisfied with their LP. Furthermore, the findings reflected the need to improve the LP. They addressed the end-users’ behavior during their journey in seeking information. Based on the use of the rich picture, these barriers have been classified into internal and external barriers. The focus was limited to investigate internal barriers. Additionally, the implementation of the SSM’s tools helps in developing the root definitions and related conceptual models that led to improving the situation of the LAIU. This study contributes to establish an appropriate and vital strategy to improve the LP based on a set of recommendation driven from the implementation of the SSM’s tools. It contributes to generate the S-diamond model addressing the requirements of improvement. It develops a model of the end-users’ ISB in the SPALs. Furthermore, this study reflects a theoretical significance by providing unique findings discovering the relationships between the themes under the investigation (EUERs, LP, end-users’ ISB, and EUS).