The international business community relies heavily on English Lingua Franca (ELF) as a shared means of communication, and English business language programmes thus feature prominently within the field of English for Specific Purposes (ESP). Business ESP programmes, however, have little focus on active listening, which previous research has pinpointed as an important negotiating skill. One aspect of listener behaviour is the use of backchannelling, for example, to signal understanding, which is central in ELF interaction. While previous corpus-based research has focused on verbal backchannelling, my analysis sees the verbal and non-verbal aspects in context, based on 13 video recordings of simulated negotiations involving 51 students from 16 nationalities (total negotiating time 3 h 46 min). Seven negotiations were carried out in an exam situation and six as coursework. The proficiency level of those participating in the former is advanced, the latter upper intermediate/advanced. Non-verbal backchannelling in the form of head nods was found to be the most frequent form, while verbal backchannelling was mainly restricted to "yes/yeah" and to items not exclusive to English, such as "mhm" and "okay." Backchannelling behaviour was also found to vary according to conflict level, as giving or withholding support may be used as a negotiation strategy. (Contains 3 tables.)