The emergence of open source software (OSS) has changed the philosophy and practice of software development, implementation and ownership; a phenomenon which also has influenced interpretations, actions and behaviors of organizational members. This research explicates the interpretations and subsequent actions of key stakeholder groups towards OSS during the implementation of an OSS-based IS in a public sector organization in Ethiopia. Drawing upon the technological frames analytical framework, the study shows that the key stakeholder groups interpreted openness of the software and the community model of software implementation differently leading them to entertain divergent actions. Users were keen to solving operational problems via readymade IS with a third party support, while the management and technologists were focusing on the strategic importance of OSS not only to their own organization but also to the nation in general. Perception differences led to alliance formation, political processes, and change of management style. The study shows that as multiple interrelated elements shape the technological frames of groups, the relationship between frame incongruence and implementation is also complex and contextual. The study proposes technological frame analysis as an integral part of OSS implementation and a carefully crafted intervention to harness frame incongruence, if any.