Although many second language learners still study in a traditional, face-to-face classroom, an increasing number of students now participate in virtual classrooms and communicate online. Regardless of the mode of communication, interaction and focus on form can be considered important components of the learning environment. This paper reports on a study comparing teacher and student interaction on a single communicative task. Three groups of teachers and students in a private language school in New Zealand conducted the task in a face-to-face context. Another four groups in a writing course at the University of Auckland conducted the same task in an online chatroom. Two of these groups included the presence of a teacher (moderated), while two groups consisted of only students (unmoderated). The frequency and characteristics of focus on form episodes (FFEs), in which participants took "time out" to focus on linguistic form, was analysed. The results indicate that focus on form occurred in all three contexts; however, it was most frequent in the face-to-face context and least frequent in the unmoderated context. In addition, the majority of the FFEs were in response to learner errors and targeted both grammar and vocabulary. Finally, the use of emoticons and chat language in the teacher-moderated online context received considerable attention in the interaction. (Contains 3 tables.)