In their examination of ESL teachers' questions in the classroom, Long and Sato (1983) found that teachers ask significantly more display questions, which request information already known by the questioner, than referential questions. The main purpose of the study reported in this article was to determine if higher frequencies of referential questions have an effect on adult ESL classroom discourse. Four experienced ESL teachers and 24 non-native speakers (NNSs) participated. Two of the teachers were provided with training in incorporating referential questions into classroom activity; the other 2 were not provided with training. Each of the 4 teachers taught the same reading and vocabulary lesson to a group of 6 NNSs. The treatment-group teachers asked significantly more referential questions than did the control-group teachers. Student responses in the treatment-group classes were significantly longer and more syntactically complex and contained greater numbers of connective.