This repeated-measures, counter-balanced study reports on a comparison of quantity and quality of one teacher's language in face-to-face (FTF) and written electronic (WE) discussions with advanced English as a Subsequent Language (ESL) students. Transcripts from the two types of discussions were compared for complexity of teacher input and the language functions this input served during the discussions. Analyses show that the teacher contributed more words, more t-units, and longer t-units to the FTF discussions, and his contributions were longer, consisting of more t-units. The teacher's input to the FTF discussions, unlike the WE discussion, created inequality in participation in the whole group. In the WE setting, teacher language encouraged interaction with individual students, while in the FTF setting, it tended to promote interaction with the whole group. Categorization and analysis of the language functions used showed statistically significant differences. (Contains 7 tables, 2 figures and 5 notes.)