This article analyses how robot–learner interaction in robot-assisted language learning (RALL) is influenced by the interaction behaviour of the robot. Since the robot behaviour is to a large extent determined by the combination of teaching strategy, robot role and robot type, previous studies in RALL are first summarised with respect to which combinations that have been chosen, the rationale behind the choice and the effects on interaction and learning. The goal of the summary is to determine a suitable pedagogical set-up for RALL with adult learners, since previous RALL studies have almost exclusively been performed with children and youths. A user study in which 33 adult second language learners practice Swedish in three-party conversations with an anthropomorphic robot head is then presented. It is demonstrated how different robot interaction behaviours influence interaction between the robot and the learners and between the two learners. Through an analysis of learner interaction, collaboration and learner ratings for the different robot behaviours, it is observed that the learners were most positive towards the robot behaviour that focused on interviewing one learner at the time (highest average ratings), but that they were the most active in sessions when the robot encouraged learner–learner interaction. Moreover, the preferences and activity differed between learner pairs, depending on, e.g., their proficiency level and how well they knew the peer. It is therefore concluded that the robot behaviour needs to adapt to such factors. In addition, collaboration with the peer played an important part in conversation practice sessions to deal with linguistic difficulties or communication problems with the robot.