A study examined the classroom communication behaviors adult learners and traditional undergraduate students associate with highly effective and highly ineffective instructors. Subjects, 155 traditional undergraduate students (68 males and 87 females) and 95 adult learners (23 males and 71 males) at a large midwestern university, rated the communicator style and power bases used by either a highly effective or highly ineffective teacher. Results indicated that both groups of students agreed on the communicator style and power variables that characterize a bad teacher. However, the two groups differed in their perceptions of how good teachers communicate and use power in the classroom. (One table of data is included.) (Author/RS)