In problem-based learning (PBL), collaboration and productive interactions among group members are not spontaneous processes. One way to support students in PBL is to integrate self- and peer assessment to assess group members' contribution to solving the problem. The purpose of this case study was to determine the perceptions of Bachelor of Education preservice geography teachers of their own as well as their fellow group members' contribution in a geography PBL activity. The study used a quantitative research method based on assessment rubric application where geography preservice teachers were asked to provide an assessment on their own and fellow group members' contribution, which included leadership, collaboration, initiative, attitude, effort, research, communication and a written report as well as individual tasks. The results indicated that effort, attitude and collaboration received the highest scores in self-assessment as well as peer assessment. Interestingly, the preservice geography teachers gave higher scores for their contribution to themselves, in comparison to peer assessment. No real gender differences in the self- and peer assessment of male and female preservice teachers' contribution occurred in this study. The female preservice geography teachers received higher scores for most of the criteria in both self- and peer assessment compared to the male participants.