Comprehensive institutions (CIs) have long been characterized as middling universities with a confused identity and purpose. Yet, their historical origins demonstrate that they have served as an important point of access into higher education for marginalized student groups. Still, there remains little consensus over which institutions are CIs and what organizational characteristics are associated with being an CI. This study uses novel data on institutional comparison groups and a network approach to determine which institutions other U.S. colleges and universities define as CIs. The analysis provides a method for detecting culturally-defined organizational categories and clarifies the definition of a CI. Creating analytical clarity about which institutions are CIs has important implications for future research on these institutions and for policy that affects these institutions.