The thesis addresses the importance of the biographical in questions relating to professional development arguing that biography illuminates how individuals acquire knowledge and how perspectives on development are formed. From a perspective of Developmental Systems Theory change and development for teaching is viewed as selfreflexivity — a more contextually relevant concept than self-understanding. In exploratory interviews, different temporal orientations between teachers emerge. Extended, interpretative interviews take place employing an interview guide to test the link between biography, knowledge acquisition, practice and development. Five case studies are developed featuring teachers chosen for their diversity and interest and potential to contribute to an emergent theory. Respondents have been teaching colleagues for an average of ten years. A major theme is a differentiated ability to integrate past and present. This also relates to the degree of self-reflexivity. In addition, it is associated with a more differentiated approach to the future and development. Those embracing the future are more inclined to work collaboratively, have a flexible student oriented approach to planning and practice and are likely to engage in critical reflection. From this perspective, teacher development should emphasise goals of coherence and complexity. The process of dialogue is a crucial means of facilitating these. Key elements in a possible design for dialogue are developed through interviews and observations focusing on teacher learning experiences. Different pathways to dialogue relate to different biographical profiles and learning maps. Pathways for facilitating dialogue amongst teachers with a past time orientation are proposed. The model of development through dialogue so constructed meets the challenge of the present and allows individuals and organisations to negotiate the future with confidence.