This paper reports on a case-study on the implementation of “language games” as a pedagogical tool for analyzing, assessing and promoting the quality and the level of collaborative knowledge building in online learning dialogues. Part of the overall objective is to explore the use, strength, weaknesses, and limitations of using the method in the context of an online senior level university course (on-campus and off-campus continuing education) on Global Change. In this investigation, the insight from using a theoretical perspective of language games is elucidated and discussed in relation to the benefits of other theoretical approaches. Applying an analytical perspective of language games, sequences of online dialogues are analyzed in order to understand their specific characteristics and to diagnose the quality of the collaborative knowledge building processes. To what extend do language games reveal true knowledge building in an online learning environment? Results of this study suggest that language games may function as a tool for diagnosing quality in online collaborative knowledge building processes. Furthermore, their possible use as an instructional tool for promoting more authentic collaborative online learning is discussed.