Although there have been a number of studies on large scale implementation of proprietary enterprise information systems (EIS), open-source software (OSS) for EIS has received limited attention in spite of its potential as a disruptive innovation. Cost saving is the main driver for adopting OSS among the other possible benefits including security and reliability, transparency of development process, etc. Due to the costly implementation of proprietary EIS, small- and medium-sized organizations have given attention to OSS as an alternative. OSS EIS can also help create a competitive advantage by enabling organizations to customize their information systems by modifying the open-source software codes without the dependency on vendors. Prior OSS related studies focused mostly on the desktop software, database management systems (DBMS), web server software, and operating systems (OS) to exploit the motivation of OSS developers, social structures, collaborations in OSS development communities, etc. The present research project conducted a confirmatory analysis on enterprise application built by open-source communities by adopting an information system success model that primarily relies on constructs that consists of user perspectives on OSS EIS that organizations have adopted. This research consists of a two-phase qualitative/quantitative mixed method. The first phase investigates the frequencies of EIS modules that have been developed in OSS communities to find the most widely applied functions of OSS EIS. The second phase of the research examined the success factors of OSS EIS based on an IS success model. The study used a sample of OSS EIS users. Users of popular OSS EIS were surveyed about the quality of the system, the information from the system, the community service, the user satisfaction, individual net benefits, and the organizational net benefits. The results suggest removing several constructs entirely from the model proposed by this research and building a new simplified OSS EIS success model. [The dissertation citations contained here are published with the permission of ProQuest LLC. Further reproduction is prohibited without permission. Copies of dissertations may be obtained by Telephone (800) 1-800-521-0600. Web page: http://www.proquest.com/en-US/products/dissertations/individuals.shtml.]