Concept mapping with Learning Tool, a computerized mapping program, was used to assess changes in the content and organization of 17 preservice teachers' concept maps for the topic of effective teaching. Preservice teachers in their senior year of an early childhood teacher education program constructed and revised concept maps with a partner. They entered reflections on each mapping experience into their reflective journals, developing implications for teaching. Analysis of the concept maps revealed that these students had a primary concern with classroom management throughout the year, linking diverse information to that concept. They evidenced detailed and diverse understandings under the labels of knowledge and organization. Professionalism was a common item, though it was less well developed. Their reflective journals indicated that these students moved from describing emotional reactions to using the computer program as a basis for reflection on the teaching/learning process. This study illustrates how concept mapping can be useful in describing students' evolving constructions of knowledge in a particular subject area, and in promoting reflection.