For the last decade, Steven Farr and his colleagues at Teach For America (TFA) have studied the most highly effective TFA teachers--those whose students make remarkable academic progress. In this article, Farr describes the qualities that distinguish these great teachers from less effective TFA teachers. They have identified six leadership principles that enable these teachers to transform the lives of students in high-poverty schools: setting ambition goals, getting students invested in learning, planning purposefully, executing effectively, continually increasing their own effectiveness, and working relentlessly. Although these teachers "are forging a path to broader opportunities for their economically disadvantaged students," Farr points out that closing achievement gaps will require not only the heroic efforts of individual teachers but also strong school leaders and systems that are built around these same leadership principles. (Contains 1 endnote.)