Harkness teaching is the pedagogy of all history classes and, indeed, of all classes in all disciplines at Phillips Exeter Academy (PEA). It can be somewhat difficult to arrive at an exact definition of "Harkness teaching." Loosely speaking, Harkness teaching is leading student-centered discussions in class, finding ways to get students to make the discoveries for themselves, to get them to draw their own conclusions, to teach them how to consider all sides of an argument, and to make up their own minds based on analysis of the material at hand. Harkness teaching tries to develop in students their own sense of responsibility for their education. The teacher is the cultivator of that sense of responsibility, rather than the fount of information and analysis. Harkness teaching dates back to the late 1920s, when philanthropist Edward Harkness approached Dr. Lewis Perry, PEA principal, with an offer to fund whatever program the faculty of Exeter could devise that would improve American education. The only condition placed on this gift was that the teaching had to be new and it had to be innovative. The faculty worked at this challenge for several years and eventually went back to Mr. Harkness in 1930 with a plan to change Exeter's contemporary pedagogy of teacher-centered classes in which the students sat in rows and listened to the "experts" at the front of the class. Instead, the boys (Exeter was an all-boys school at the time) would sit around tables and discuss the material. In a letter to Mr. Harkness, Dr. Perry explained the vision of the new Harkness Plan: "The net result would be that the boy would become more grown-up, would think of his studies as something more real, and would have an interest, a compelling motive, which he would carry to college. The successful teacher in the conference plan would not be a drill master, but a partner in a human enterprise." In this article, the authors consider what they do at PEA as Harkness history teachers, offer their thinking about leading discussion in the history classroom from their perspectives as teachers at PEA, and share what they have learned by working in the Exeter Humanities Institute. (Contains 15 notes.)