This study examined the teaching of controversial public issues (CPI) in middle and high school social studies classes. I sought to better understand the instruction and conceptions undergirding the instruction of secondary social studies teachers who were nominated by discussion experts as especially skillful at teaching their students to participate more effectively in CPI discussions. Using grounded theory, l analyzed three types of data: classroom observation field notes, interviews of the teachers, and CPI discussion teaching artifacts. First, I describe CPI discussions in the teachers' classes, then introduce six propositions induced about the teaching of CPI discussions. Next, I discuss how the propositions challenge and add to the existing literature on classroom discussion in secondary social studies, and suggest implications for the CPI discussion teaching practice of teachers and teacher educators. (Contains 2 notes.)