The term “Vulnerable populations” generally refers to research participants whose diminished autonomy renders them particularly susceptible to coercion, undue influence, mistreatment, or exploitation in research contexts. This chapter examines arguments for the utility of distinguishing this category of research participants, as well as critiques of the concept. It then reviews existing scholarship to derive suggestions for best practices for interviewing vulnerable people. Along the way, it emphasizes the critical value of deep contextual knowledge of researched communities to help researchers understand the circumstances creating vulnerability, recognize signals that participants are susceptible to or experiencing harm, and respond accordingly to make research both ethical and valid. Throughout, the chapter offers examples from my own experience doing interviews with Syrians displaced by war since 2011, as well as with Palestinians in the West Bank and Gaza Strip about their experiences of occupation and violence.