Instructional communication research may be examined from the perspective of teacher effectiveness research, based on three dominant 20th-century philosophical traditions: logical empiricism, interpretive theories, and critical theory. Since at least 1896, scholars have used empirical research methodology (largely "logical empiricism," modeled after the approach of the natural sciences) to shed light on what it means to be an effective teacher. Approaches have ranged from naturalistic descriptions of teacher classroom behaviors to tightly controlled experiments that manipulate such variables as teacher clarity in order to assess their impact on student learning, and have included examining teacher evaluation rating scales and studying the cognitive processes that mediate instructional stimuli and learning outcomes. As a result of the criticisms against logical empiricism, other researchers are beginning to use interpretive inquiry, that is, observing and analyzing human behavior in natural settings to discover what and how people learn through interacting with others. Finally, the critical inquiry approach takes into account historical-ideological movements. Despite this diversity of approaches, however, the vast majority of instructional communication research has been conducted from within the trait-rating tradition of empirical inquiry. While success in these efforts is important, the usefulness of instructional communication research is likely to be enhanced by encouraging the use of other research methodologies. (HOD)