The study aimed at providing evidence for the development of children's beliefs about everyday reasoning. A total of 116 third, fifth, and seventh graders participated in the study. They were examined individually with 14 everyday thinking scenarios which have been developed by Amsterlaw (2006). After each scenario, children were asked to evaluate the quality of each way of thinking and to explain their evaluations. The results showed that children as young as 8-9 years have a well-developed awareness of good and bad thinking processes in everyday situations. Further, they indicate an emergent ability in fifth graders to give process-focused explanations. (Contains 1 table and 2 figures.)