Research on teaching has recently focused on the cognitive aspects of teachers' work, using a variety of verbal report procedures. It is argued that the models implicit in this research frequently underestimate the complexity of teachers' professional thinking and that teachers' verbal report data reveal characteristics of teaching which research on teachers' cognitions fails to acknowledge. It is suggested that a closer examination of the nature of verbal reports and of their status, and a more critical examination of the models that have been brought to the investigation of teachers' thinking, is required in order to lead to any conceptual advance in this area. (Author)