The use of computer-support collaboration appears to be highly potential for language learning and acquisition as well as for research. This study examines foreign language reading and vocabulary acquisition, focusing on the potential of collaboration among learners in acquiring unknown vocabulary words encountered in reading. Platform features supporting collaboration such as scaffold-building and annotation are exploited to foster adult English learners use of context-based top-down strategies in guessing unknown words and to reduce their reliance on direct translation as a reading strategy. Novel adaptations of Knowledge Forum are implemented for this purpose, and a community-of-practice approach to collaboration is examined. Seeding the platform with a model example for approaching unknown words succeeded in propagating novel strategies among groups of the learners. Moreover, community-of-practice groups showed a statistically significant preference for using the target language rather than translation in approaching unknown words compared to traditional groups.