We sought to examine empirically the prevailing assumption that changing assessment can leverage curricular reform. This assumption has been significantly confirmed by our research for the case of mandated high-stakes assessment. Two studies were conducted in the two most populous Australian states, New South Wales and Victoria. In the final two years of secondary school in both states, courses of study and assessment arrangements are mandated for all schools, including the private sector, by the state's Board of Studies. Congruence between mandated assessment and schoolwide instructional practice was found in two states whose high-stakes assessment embodied quite contrasting values.