With a growing demand for learning English and a trend of utilizing computers in education, methods that can achieve the effectiveness of computer-mediated communication (CMC) to support language learning in higher education have been examined. However, second language factors manipulate both the process and production of CMC and, therefore, attention is required when discussing factors influencing CMC in a second language setting. This paper discusses text-based CMC in an English-as-a-foreign-language (EFL) context and examines correlations between items included in CMC measures via a second language. Results show that CMC measures and second language proficiency are statistically correlated at a significant level. Some key points raised here are (1) a computer user's second language writing proficiency influences the computer communicative skills that he or she applies to the online dialogues; (2) a computer user's second language proficiency is related to his or her self-perception of the achievement on online dialogues; and (3) an EFL computer user's motivation for CMC is connected to his or her second language writing ability.