Although public education is a constitutional responsibility of state government, state policymakers historically delegated this authority to local school districts, particularly in matters of curriculum and instruction. District policymakers, in turn, usually entrusted the curriculum to teachers or textbook publishers, and hired few district staff to develop or provide instructional guidance (Walker, 1990; Rowan, 1983; Crowson and Morris, 1985). Typically, when state or district policymakers did provide direction, they limited it to bare listings of course requirements or behavioral objectives. Few systems prescribed topics within courses or curricula; guidelines about teaching pedagogy were even rarer (Cohen and Spillane, 1993). In marked contrast to this long historical pattern, states and districts have made unprecedented forays into curriculum and instruction during the last twenty years. Even within this short period, however, their policy approaches have changed rapidly, shifting both in terms of student learning objectives and the kinds of strategies they used to encourage local instructional innovation. Whereas in the late 1970s, state policymakers instituted minimum competency tests to ensure that students learned a modicum of basic skills, by the early 1980s they began to expand both the subjects and grade levels tested. They also pushed through increases in credit requirements for core academic subjects as prerequisites for graduation. In the late-1980s, state and district policymakers (along with many professional subjectmatter associations and private foundations) turned their attention from the number of academic courses to the quality of the core academic content being taught in public schools. They undertook this effort primarily in response to international test results and domestic studies, which indicated that even our academic courses were relatively weak and offered students little opportunity to apply knowledge (Porter et al., 1993; Elley, 1992; Organization for Economic Cooperation and Development, 1992; Kirst, 1993; National Center for Education Statistics, 1992).