Fairly large amount of research on students' conceptions of probability has been reported in the literature. Most of this work represents school students' reasoning of probability in individual setting. This study provides 8 secondary school mathematics preservice teachers' reasoning of probability in both individual and pair settings. Consistent with previous studies the findings of this study indicate that preservice teachers' conceptions of probability are often different across settings. However, a few preservice teachers who strongly believed in formal reasoning provided consistent argument across all settings if similar tasks were presented. It is suggested that the teaching of probability should provide an opportunity for students to interact in both individual and group settings. [For complete proceedings, see ED500858.]