The aim of this study is twofold: to analyze politeness strategies in the online conversations of Thai students, and to suggest how this analysis can be applicable to pedagogical practice. A corpus of a 21-month instant online conversation among students and teachers has been analyzed. Throughout the time of data collection, the teachers continually encouraged students to use English and French to promote the use of foreign languages that they were learning. The result of statistical analysis showed the relation between speech acts and politeness strategies used in the data. It could be claimed that the students' language proficiency governed their politeness strategies. As a result, the authors proposed a modification of Brown & Levinson's (1978) Weightiness formula for non-native speakers of English as: W[subscript x] = LP(S) × [D(S,H) + P(H,S) + R[subscript x]]. The results also showed that emoticons were used as redressive actions in politeness. Further, interlanguage pragmatics in the data were discussed based on linguistic competency and socio-cultural norms in the participants' L1. The results suggest that teachers and curriculum developers could better understand students' communication behaviors and language competency through computer-mediated communication. Finally, we offer suggestions to promote online communication in the context of active learning.