The present research aims to identify the depth of reflection attained by primary school teachers through the Critical Incident Technique (CIT) according to the categorisation of Lee (2005) and specific factors that could determine a higher level of reflection. For the first research phase twenty teacher semi-structured interviews were conducted. The results so far indicate that the majority of participants tend to reflect at Rationalisation Level while a small percentage of the sample were considered to have attained Reflective Level, in accordance with Lee's three-level categorisation of reflective thinking depth (namely Recall Level, Rationalisation Level, Reflective Level). The research also highlights specific factors, such as age, level of education, years of teaching experience that have a crucial impact on teachers developing a higher level of reflection.