Gangs present serious challenges to the management and order of prisons. Restrictive housing is viewed by correctional officials as one of the few effective responses to gangs, yet public officials and advocates continue to push for reductions in its use. Some evidence suggests gang affiliates are overrepresented in restrictive housing, although this research is limited to a few prison systems, and the reasons for this relationship remain speculative at best. This study examined the relationship between restrictive housing and gang affiliation based on administrative data gathered from 39 correctional agencies in 2016, collectively housing 73% of state prisoners. The relative risk of placement in restrictive housing was 3 times greater for gang affiliated than non-gang inmates. Over one-third of the inmates in restrictive housing were gang affiliated. While gang affiliates were overrepresented across all of the primary pathways into restrictive housing, the risk was greater for administrative purposes (6.3) than for disciplinary (3.1) or protective (2.6) purposes, although substantial variation existed across prison systems. The quest to reduce the footprint of restrictive housing in U.S. prisons cannot occur without accounting for one of the most difficult populations for correctional authorities to manage, that is, the 213,000 prisoners affiliated with gangs. The challenge will be greater in prison systems with larger custodial populations, a higher proportion of confirmed gang affiliates, higher rates of gang-related violence, and longstanding histories of gangs, where restrictive housing is more likely to be used disproportionately. Programs and practices aimed to reintegrate gang affiliates back into general population housing are deserving of research and evaluation owing to their implications for institutional and community corrections.