Interpersonal teacher behavior can be described with the Interpersonal Circumplex on the dimensions of communion (warmth, sensitivity) and agency (initiative, control). In an observational study, we investigated whether a teacher's interpersonal behavior in dyadic interactions with a student is complementary to the student's communion and scholastic competence: Does the teacher act communal to the extent that the student behaves communal, and does the teacher act more agentic the less competent the student is? In 39 primary and secondary schools, we conducted direct classroom observations for two teacher-student dyads each (78 dyads). Using Structural Summary Method, we found as expected that teacher communion was positively associated with student communion, to the detriment of students who have not yet learned to behave in a communal manner. Further, results showed a negative association between teacher agency and student competence, suggesting that teachers engaged in adaptive teaching. Results further showed that weak teacher communion was related to low student competence. We discuss the implications for teacher education and training, namely that teachers should be trained to prevent falling into patterns of dysfunctional, non-communal behavior when confronted with a particular set of student characteristics and behaviors.