Participation in the Organization for Economic Co-operation and Development's (OECD) Program for International Student Assessment (PISA) has continuously expanded: from 43 systems in 2000 to 65 systems in the 2012 cycle, with 71 signed up for PISA 2015. There also has been a growth in sub-national participation, expanding PISA's reach beyond the nation-state. This paper explores sub-national PISA participation in Canada and the USA, asking "how" PISA is being used within sub-national education policy spaces. We draw on analysis of documents and data from interviews with officials at sub-national, national, and international levels. Findings illustrate some of the diverse motivations and uses of PISA, providing insights into the effects of PISA at the sub-national scale. As such, we argue that competitive comparison in education has deepened through the enhanced granularity of international large-scale assessment data to new scales beyond the nation-state.