The explosion of the World Wide Web; dynamic nature of information technologies, such as open source; the increase in electronic resources; and the rising expectations of library users have contributed to the changing nature of the Automated Library System (ALS) since its inception in the  1970s. These changes are reflected in the conceptual differences between the ALS and the Integrated Library System (ILS). The ALS is identified as simply a database to house and retrieve a library’s holdings while ILS is identified as robust clusters of systems involving every process and module related to library operations. This article presents a review on the evolving features of some commonly adopted Open-Source ILS Software (Koha, NewGenLib, Evergreen, PMB and OpenBiblio) which had stirred ALS to ILS, as well as justifications and barriers to the use of open source software in academic libraries. Keywords: Automation, integrated library system, library, software