Reflection and change are pivotal themes in this paper, which outlines the rationale, methodology and principal findings of a research undertaking on teacher development in Ireland. The study was based on the premise that teachers' practices are guided in large measure by a "tacit knowledge" of education, formed in response to personal and contextual factors. It was held that sustained teacher and school development relate primarily to acquiring an awareness of and engaging in ongoing reflection on this implicit theory. Participants were facilitated in structuring such reflection through images--as subjective knowledge structures which capture their latent understandings of teaching and learning processes. It was an enlightening and empowering experience for the teachers involved, who, as a consequence, could both envision and initiate necessary improvements in their educational practices. The findings have notable implications for pre-service and in-service teacher education. (Contains 6 figures. )