Vulnerabilities often characterize the availability of immigrant populations of interest in social behavioral science, public health, and medical research. Refugees, asylum seekers, and undocumented immigrants present unique vulnerabilities relevant to protocol development as well as ethics review procedures and criteria. This paper describes vulnerable populations in relation to the Belmont Report and US federal regulations for the protection of human subjects, both of which are commonly used in international research contexts. It argues for safeguards for immigrants comparable to protections for (...) such populations as pregnant women, prisoners, and children. The paper further presents a two-part model for the review of protocols that involve immigrants. The model is intended to help identify the risks to immigrants associated with participation in research, and to suggest how researchers can responsibly frame studies and access to research participant immigrants through community-based, and/or non-governmental organizations that serve immigrants and immigrant communities. (shrink)