Constructing an appropriate group is important to teamwork success. Although, heterogeneous grouping is widely recommended in Western countries, this method of grouping is questioned in Asian classrooms because Asian and Western students have different cultures of learning. Unfortunately, this issue has not been addressed in any research to date. This study aims to investigate how Vietnamese students should be grouped so that they can maximize their opportunities to learn. The study is in two parts: a pilot study and an intervention. The pilot study included twenty students and was conducted for four weeks. The intervention consisted of one hundred and forty five students and lasted for eight weeks. In both studies, students answered a questionnaire survey and ten students were interviewed. The results of both studies showed that friendship grouping was more preferred. Future researchers should take these findings into consideration so that cooperative learning activities can be designed adaptively in Asian classrooms.