This thesis investigates issues related to the development and implementation of OSS (Open Source Software) for health care in developing countries. The aim is to understand why the same OSS technology for health care leads to varying outcomes in different developing countries, and how to find effective ways to organize it. A theoretical perspective inspired by the Social Construction of Technology (SCOT) theory was employed to set a base for the analysis process. A comparative case analysis was carried out over the development and use processes for two OSS applications (DHIS 2 and patient based systems) that were both developed and use in two developing countries – Ethiopia and Vietnam, Four comparative case studies (across countries and across systems) thus emerged. Social conditions inferred from the SCOT literature that served as the point of departure for the starting point of my analysis included 1) Team structure and organization, 2) Technical capacity, 3) Nature of thesector 4), and Technology introduction process. The study was informed by qualitative methods, and carried out within an action research framework over the period of 2005-2006. Through the analysis process, three main categories of social conditions relevant in shaping the outcomes were identified, which are 1) Technical Infrastructure, 2) Organizational Arrangements, and 3) Development Process. Points of departures between my theoretical inferences and as seen in the traditional SCOT literature were identified such as the level of internet dependence and the dedication and commitment of developers. These conditions were seen to be specifically relevant to the empirical domain characterized by OSS, developing countries and health care. In making these inferences, this thesis makes a contribution to the domain of social analysis of OSS applications. Practically, the research suggests implications in managing OSS projects for health care in developing countries such as emphasizing the role of appropriate team organization and structure, managing thetechnology introduction process, strengthening the link between development and use, and sensitively cultivating the support from the network.