In recent years, policy changes in American education have refocused a spotlight on principal instructional leadership. Although in previous eras the professional literature exhorted principals to "be instructional leaders," there were few sanctions if they failed to do so. In the current policy context, however, instructional leadership has assumed a central rather than peripheral place in the hierarchy of roles played by principals. Today principals who fail to engage this role proactively and skillfully do so at their own risk. Yet history suggests that neither policy mandates nor good intentions will penetrate the "force field" that stands between the principal and the tasks involved in leading learning. A more strategic and coherent approach is needed by principals who wish to enact this role in practice. This article reviews the evolution of instructional leadership as a model for principal practice, examines barriers to its successful enactment, and proposes strategies that school leaders can employ to reduce the gap between intentions and reality. (Contains 1 figure.)