Institutional review boards, tasked with facilitating ethical research, are often pulled in competing directions. In what we call the protection-inclusion dilemma, we acknowledge the tensions IRBs face in aiming to both protect potential research participants from harm and include under-represented populations in research. In this manuscript, we examine the history of protectionism that has dominated research ethics oversight in the United States, as well as two responses to such protectionism: inclusion initiatives and critiques of the term vulnerability. We look at (...) what we know about IRB decision-making in relation to protecting and including “vulnerable” groups in research and examine the lack of regulatory guidance related to this dilemma, which encourages protection over inclusion within IRB practice. Finally, we offer recommendations related to how IRBs might strike a better balance between inclusion and protection in research ethics oversight. (shrink)