This study analyzed differences in perception of "critical incidents" in classroom teaching among inexperienced, experienced, and award-winning university professors. In past research, expert and novice differences in teaching have been attributed to differences in teacher knowledge, but the teachers were almost entirely at the elementary or secondary levels rather than the post-secondary where instructors have subject matter expertise rather than formal training in teaching. Analysis was based on a total of 102 questionnaire responses, all from full-time university instructors, fairly equally distributed among the three experience levels. Each summarized response was coded to characterize the professor's concerns and thinking associated with a memorable teaching incident, using the categories of: (1) knowledge, which could be information about students or about an instructional strategy; (2) processes, as pacing, or awareness of student comprehension levels; (3) goals, or desired outcomes; and (4) actions, or activities. The study found that, while categories used in the coding process could be hypothetically separated, it was frequently difficult in practice. There was much overlap between groups in the categories suggesting that the same category may have a different context in the different stages of a teaching career. Results have implications for faculty development activities. The Critical Incident Questionnaire is attached. (Contains 26 references.)(BF)