In this paper, research on teachers' judgments, instructional planning, and decision making during classroom interaction is reviewed. Research studies chosen for this paper were selected on the basis of two fundamental assumptions: (1) Teachers behave reasonably in making judgments and decisions; and (2) Their behaviors are guided by their thoughts, judgments, and decisions. Research methods used in the studies include policy capturing, lens modeling, process tracing, stimulated recall, case study, and ethnography. It is noted that it was difficult to evaluate some of the individual studies examined, so that replicability was used as a criterion for inclusion. If studies which, individually, could not be evaluated adequately on methodological grounds produced consistent results, they were included. Sections evaluating research studies on teachers' judgments, planning, and interactive decision making are followed by a section containing annotations of the 25 research studies reviewed. (JD)