This thesis is an empirically based, theoretical discussion of the process of decision making in relation to Library Management Systems (LMS). Although the conceptualization of the LMS decision process in rational terms, common in many LMS selection models, may be useful in different respects, here the process is viewed from a social constructivist stance. It is argued that due to the complexities involved, the potential choice of an LMS does not necessarily reflect the superiority of the chosen LMS based on objective inherent qualities. Nevertheless, libraries continually choose new systems and in many of these selection processes, the chosen system is perceived as the optimal choice. In this study, therefore focus is placed on examining the way in which this shared perception is constructed. Three theoretical views are adopted as the research framework, including Brunsson’s views on the process of decision making and its consequences, Collins’s views on methodological symmetry and construction of conceptual order, and finally Giddens’s views on duality of structure and the social order. Observations, interviews, and document studies are the methods employed in four different case studies that each lasted from 10 months to two years. In this study an array of different factors were found to be influential during the long process of the LMS decision making. It was also found that although the norms of rationality were striven for, and shared perceptions of rationality were constructed, the complexities involved did not allow a true rational choice by determination of all the options, projection of future needs, evaluation of the identified options, and selection of the optimal outcome. Instead, the different activities and happenings during the process helped construct a shared perception of the possible courses of action and optimality of the decision outcomes. Based on this study and with the help of the theoretical framework, it was suggested that an LMS choice is only one potential consequence of the LMS decision process; other consequences include legitimization, action, responsibility, and constructions of conceptual and social order. Through this study, the importance of the day-to-day actions and interactions (at micro level) and their wider implications for the construction of shared perceptions and shaping and reshaping of social structures are highlighted. This thesis contributes towards an alternative conceptualization of the process of LMS decision making. It may also have implications for the library practice, LMS related research, and educational programs within LIS.