This collaborative action research study examined the development of critical thinking when the See, Think, Wonder thinking routine was implemented in a preschool classroom. One preschool teacher undertook this research with 13 preschoolers (aged 3-4 years). The thinking routine was conducted as an in-depth group discussion during circle time. The data collection for the research included field notes, vignettes and document analysis. The results indicated that the routine promoted critical thinking skills in preschool aged children.