This article extends the Institutional Analysis and Development Framework's seminal research on common pool resource (CPR) management in new directions by exploring how the design principles of robust and enduring CPR management, initially proposed by Elinor Ostrom in 1990, can be used to measure and assess cross-scale institutional linkages. This study examines data from 14 interstate river basin compacts in the western United States to identify the types of linkages established in these interstate settings, the factors that contribute to the emergence of diverse types of linkages around these shared resources, and how different types of linkages perform. Using Ostrom's CPR design principles to operationalize and measure linkages, the study shows that diverse types of cross-scale linkages were created under the 14 interstate compacts, with linkages related to monitoring found to be particularly prevalent. The types and diversity of linkages can largely be explained by the conditions under which compacts emerged and the water management issues states jointly face. In applying the evaluative criteria operationalized by the CPR design principles, this research further shows that the monitoring and collective choice linkages created by compacts tend to be of higher quality, while enforcement and conflict resolution linkages appeared to be of the lowest quality. In addition to developing the IAD literature on CPR management, these findings offer critical insights for assessing the capacity of interstate river basin compacts in the western United States to manage shared resources successfully, as well as insights for what types of institutional investments may be needed for enhanced resource governance.