This study reports on pupils' and teachers' perceptions of face-to-face promotive interaction (FtFPI) in cooperative learning (CL) at two primary schools in post-war Bosnia and Herzegovina (BiH). Using mixed methods, the study asks (1) 'To what extent are the aspects of FtFPI most likely to influence pupils' CL group work?' (2) 'What are the challenges in applying pupils' FtFPI in small CL groups?' The findings reveal mostly positive beliefs of FtFPI influence on small CL group work. However, when it comes to pupils' and teachers' experiences, several challenges have been identified: (1) organisation of FtFPI, (2) planning and balancing between working on a group task and supporting peers, (3) interpersonal behaviours, and (4) supportive communication. The findings suggest that more classroom research related to peers' promotive interpersonal behaviour and supportive communication is needed.