One element of the design of human research studies is ethically informed decision-making. Key issues include the safety, costs, and benefits of participation. Historically, much of this decision-making was based on opinion rather than formal evidence. Recently, however, investigators in the traumatic stress field have begun to collect data that are relevant to these decisions. In this article, the authors focus on issues emanating from the ethical concepts of autonomy and respect for persons and beneficence and nonmaleficence, and then summarize relevant evidence from studies with trauma-exposed individuals. Discussion addresses implications of this evidence for research practice and policy, and identifies some potentially informative data collections opportunities for future trauma studies.