Despite the importance of reflection on critical incidents (CIs), there are only a few studies in ELT literature addressing English language teachers' CIs (Farrell, 2008). Accordingly, this study was conducted to explore and discuss how six in-service EFL teachers reflected on and reported their CIs. In so doing, the participant teachers reflected retrospectively and introspectively on their CIs for 12 sessions. They put their CIs in a blog each session in order to share them with their colleagues. After the treatment, the three stages of grounded theory were employed in order to analyse the CIs. The results, revealing six categories and 12 subcategories, shed light on the "what" and "why" of teachers' reflections on their CIs. Results may have implications for teacher education and can add to the existing literature on unpacking teachers' CIs.