English-medium instruction classes in higher education are increasing in countries where English is not the first language. Though these courses offer advantages, they also offer concerns and challenges. One of these challenges is creating a rapport between a teacher and students who are working in a language that is not their own. Rapport is important because it has been linked to academic performance. This study explored possible differences in rapport between two groups of students who were taking a class on Communications Research at a Mexican university. One group took the class in their native language, Spanish, and the other one took the class in English. The teacher, the programme, and the materials were identical in both cases; they only differed in the language of instruction. The study is qualitative in the ethnographic tradition. Videos of classroom interactions were used as a data source, which were analysed and coded. Codes were based on rapport-building activities. The teacher's log and the nine-item Student-Instructor Rapport scale complemented the study. The videos showed evidence of rapport-building activities in both the Spanish and English groups. The results of the scale showed that the students in the English group perceived a stronger rapport between the instructor and the students, than those in the Spanish group.