Professional knowledge created as teachers interact with the complexity of variables related to teaching and learning in active, thoughtful, reflective practice, is essential to expert teaching. This qualitative study is designed to describe and define the factors (processes) that are pertinent to the process of reflection as it is utilized by three expert teachers (enablers) who teach homogeneously grouped, academically gifted learners in three public school districts in Illinois. A modified form of analytic induction was employed as an approach to collecting and analyzing data as well as to developing and testing theory. Two main categories, problem solving and theory building, were derived through the analytic processing of raw data. The phenomenon of reflection in teaching was defined as thinking about teaching or reflection-on-action, and as thinking while teaching or reflection-in-action. Results suggest that reflection plays an important role in teaching; some teachers are reflective professionals who engage in a type of problem solving as they seek to integrate their value beliefs, theoretical knowledge, craft knowledge, and experience with the context in which they teach and build their own theories about teaching. (Contains 25 references.) (LL)