We investigated how students' interpersonal trust relationships impact on their willingness to share knowledge during group work and whether there is one best method of group allocation to maximise knowledge sharing. Through focus groups with 32 undergraduate and postgraduate students, we found: i) participants had limited experience of sharing skills; ii) they were more frequently engaged in sharing their beliefs, values and ideas; iii) while interpersonal relationships impacted upon the degree to which knowledge sharing took place, the major contributing factor was participants' desired outcomes. Participants identified different advantages and disadvantages for the same allocation methods depending on their motivations for attending their courses. We conclude that the most equitable approach to group work is to allow students to choose the allocation method most appropriate to their needs. Findings can assist educators in making informed decisions about group work to increase student engagement, and support cognition-based trust to enhance knowledge sharing.