The issue addressed here concerns how second language (L2) speaking strategies mediate the relationship between L2 writing strategies and the social presence component of the community of inquiry (CoI) framework within the context of fully online courses that combined learning management system (LMS) for writing tasks and videoconferencing for live classroom discussion. L2 writing strategies related to planning and reviewing contribute to composing tests that students want to upload, present, and discuss, and this sharing is expected to foster classroom social behaviors and consequent language gains. For the current study, a cross-sectional survey of 256 university students was initiated to investigate the mediating effect L2 speaking strategies have on the relationship between L2 writing strategies and social presence. The results indicated positive path coefficients between review strategies and speaking strategies, review strategies and social presence, planning strategies and speaking strategies, and speaking strategies and social presence. Further, speaking strategies explain the relationship between planning strategies and social presence, indicating full mediation. Partial mediation was found for the path between review strategies and social presence. Recognizing how L2 writing and speaking strategies relate to one another and how that relationship influences a CoI illustrates the interconnectivity between language skills. Evidently, increased attention to planning and reviewing strategies results in a final composition worth sharing and discussing, and such sharing and discussion are building blocks to a vibrant social presence.