Institutional Review Boards (IRBs) can play vital roles in observing, monitoring, and responding to research integrity (RI) issues among researchers, yet many questions remain concerning whether, when, and in what ways these boards adopt these roles. I contacted 60 IRBs (every fourth one in the list of the top 240 institutions by NIH funding), and interviewed leaders from 34 (response rate=55%), and an additional 12 members and administrators. IRBs become involved in a variety of RI problems, broadly defined, and face challenges in deciding how and when to do so. IRBs vary in how they define, discover, and respond to RI problems, and interact with other institutional offices concerning these issues; and what types of RI violations they encountered. While many institutions establish separate Compliance Offices, the boundaries and relationships between these entities and IRBs vary; and many IRBs discover and monitor RI violations, and struggle with how to respond. Larger questions arise of how IRBs decide whether to trust vs. closely monitor individual PIs. IRBs' roles are often indirect, and not fully systematic, raising questions of whether these functions should be enhanced, and if so, to what degree, and how. These areas require heightened investigation and discussion.