Based on interviews with teachers and students in Norwegian high schools, this article explores discussions of controversial issues in the classroom. Building on practice theory, it examines what enables "good" classroom discussions. The main finding is that good discussions are made possible by a productive learning environment that is jointly constructed by the teacher and students. Such a learning environment has three core elements: (1) good social relationships, (2) appropriate norms for social interaction, and (3) skillful facilitation.