Considerable efforts have been made to better understand how global trends toward standards-based reforms have emerged in national education systems. Less well known, however, is the unfolding of standards-based reforms within and across federal education systems. In federal systems, national governments do not make policy unilaterally, but rather share authority with multiple orders of government. Using the concept of "global forms" to explore the pervasiveness of standards-based assessments across four diverse federations (Australia, Canada, Germany, and the United States), this article aims to illuminate the roles that subnational governments play in the assemblage of standards-based education reforms. We argue that three key roles played by subnational governments are apparent in each: (1) semiautonomous laboratories of innovation, (2) coproducers of policy, and (3) venues for nongovernment actors. Our work suggests that greater attention must be paid to subnational spaces to better understand the manifestation, development, and expansion of global policy trends affecting education.