Computer-mediated communication (CMC) via Facebook as social media could support a relaxed and non-threatening learning atmosphere, augmenting EFL learners' engagement through increasing social interaction. To maximize the potential of CMC for English language learning outside of classroom activities, an understanding of communication flow through the lens of Social Presence indicators using Facebook group chats is needed to measure such indicators among EFL learners with a limited access to the real-life use of English. This can help enhance the quality of learning through rich interaction and increased engagement among them. The purpose of this paper was to identify Social Presence indicators used by these EFL learners in their Facebook group chats. The data were collected for eight weeks from 52 Thai undergraduate students taking an English for Conversation course in a Thai university. Using the Social Presence categories by Rourke et al. (1999) and Swan and Shih (2005), quantitative coding was used to analyze the exchanged Facebook group text messages. The results showed that the Interactive Category garnered the highest percentage compared to the Affective and Cohesive Category, suggesting that CMC with Facebook group chats engendered relationship building and sustainability among Thai EFL learners with CMC community members. Pedagogical implications are discussed on the significance of Social Presence for developing an effective CMC environment on Facebook among EFL learners.