The revised Common Rule requires using a single institutional review board (sIRB) for U.S.-based, multisite, nonexempt, federally conducted or supported research with human participants. The 21st Century Cures Act directs the Department of Health and Human Services (HHS) to harmonize differences between HHS and the U.S. Food and Drug Administration (FDA) regulations governing research with humans. Anticipating that the FDA may update its 2006 centralized IRB guidance, we conducted interviews with 34 stakeholders engaged in FDA-regulated clinical research to identify benefits and challenges of using sIRBs and to gather recommendations for revising the FDA's guidance. The main benefits were consistency and standardization, speed and efficiency, and streamlining and simplification. The main challenges were uncertainty at local institutions, including addressing local context; decreased timeliness of the research review process; variable processes; and insufficient communication. Several recommendations for FDA guidance focused on the local context and communication plans. Findings suggest that the sIRB review process may be gaining efficiency although challenges remain.