This study examines how a first-year biology teacher facilitates a series of whole-class discussions about evolution during the implementation of a problem-based unit. A communicative theoretical perspective is adopted wherein evolution discussions are viewed as social events that the teacher can frame intellectually (i.e., present or organize as exchanges of an intellectual nature). Furthermore, we characterize teacher framing of evolution discussion in terms of five communicative components: focus, orientation, social structure, mood, and participatory nature. Our video-based analyses revealed that the teacher paid little attention to the conceptual contents and history of evolutionary theory, framing evolution discussions as moderately playful and partially mandatory events focused mainly on student sharing of ideas (i.e., personal opinions) and polite communication of evolution. Within this framing, the teacher adopted the role of a neutral (though admittedly biased) facilitator with an intermediary expert status (less knowledgeable than evolutionary biologists) and who was legally required (though also inclined) to discuss evolution. The main significance of this study is that it provides new and useful insights into social phenomena such as respect, politeness, and humor in the context of evolution discussion as well as a robust theoretical framework for analyzing evolution discussion from a social perspective. (Contains 1 figure and 2 tables.)