Reflection is at the heart of continued professional development (Moore, 2002). Many educators view that reflective abilities are desirable characteristics of teachers (Gore and Zeichner, 1991; Herrmann and Sarracino, 1993). Killon and Todnem (1991) indicate in their study of in-service teachers that reflective thinking can be a tool for continued personal and professional development. My previous study (Tsui, 2004) corroborates their viewpoint. Empirical work on reflection in early childhood teachers in-service is seriously underplayed. The purposes of this study were to explore the elements of early childhood teachers' pedagogical reflection as well as factors affecting the development of reflective thinking among early childhood teachers in the authentic settings. Two beginning and two experienced early childhood teachers were recruited from four preschools in Hong Kong. All participants attended an intervention exercise within ten months. The interventions took the form of interviews, workshops and documents. Findings were emerged in the form of themes and categories: on reflective thinking, on children learning, interaction with children, teachers' teaching, curriculum issues, school context and personal characteristics. Several school factors as well as the mechanism of how these factors affecting reflective thinking and its development were identified in this study. We need to probe deeper into the factors, both school workplace conditions and personal factors.