The purpose of the study presented here was to learn more about the distinctive features of synchronous text-based computer-mediated communication (SCMC) and to determine what kinds of factors played a role in the production of such features based on the SCMC of an international group consisting of 12 people. The findings of the study indicate that participants demonstrated characteristics of both spoken and written modes of language in their SCMC. There were complex and interdependent factors beyond English proficiency that caused this variation. Some of these independent factors include attitude towards chat, keyboard control, context of the discussion, and previous experience in chat rooms. Participants' perceptions of chat room language also influenced their SCMC. Participants who viewed online written chat discourse as a type of written language wrote mainly within the norms of written language, whereas participants who viewed online written chat discourse as a type of spoken language wrote mainly within the norms of spoken language. The findings of the study imply that when study participants communicated in a chat room without specific guidance on discourse construction, they relied on their own perceptions about the communication area to form their discourse. This may have resulted in linguistic variation. (C) 2010 Elsevier B.V. All rights reserved.