Phase 1 healthy volunteer clinical trials—which financially compensate subjects in tests of drug toxicity levels and side effects—appear to place pressure on each joint of the moral framework justifying research. In this article, we review concerns about phase 1 trials as they have been framed in the bioethics literature, including undue inducement and coercion, unjust exploitation, and worries about compromised data validity. We then revisit these concerns in light of the lived experiences of serial participants who are income-dependent on phase (...) 1 trials. We show how participant experiences shift attention from discrete exchanges, behaviors, and events in the research enterprise to the ongoing and dynamic patterns of serial participation in which individual decision-making is embedded in collective social and economic conditions and shaped by institutional policies. We argue in particular for the ethical significance of structurally diminished voluntariness, routine powerlessness in setting the terms of exchange, and incentive structures that may promote pharmaceutical interests but encourage phase 1 healthy volunteers to skirt important rules. (shrink)