The relationships between Myers-Briggs Type Indicators (MBTI), 16 personality types, and 55 behavioral indicators of teacher competency were explored. Subjects were 103 classroom teachers, grades K-12, who were observed in regular classrooms during a two-year period using five objectively-scored, low-inference observation systems. These included the Spaulding Teacher Activity Rating Schedule (STARS), the Coping Analysis Schedule for Educational Settings (CASES), the Florida Classroom Climate and Control System (FLACCS), the Teahcer Practices Observation Record (TPOR), and the Observation Schedule and Record, Form 5, Verbal (OScAR 5V). Composites of items from these instruments were combined as behavioral indicators of teacher competency. Twenty-six of these scores reflected teacher activities and 29 reflected teacher competence through student behaviors. The results showed that teachers with different MTBI personality types tend to teach in the same way, but that their students respond to them quite differently. (Author/MV)