This paper introduces the term "structural coercion" to underscore the ways in which broader social, economic, and political contexts act upon individuals to compel them to enroll as subjects in clinical research. The paper challenges the adequacy of the concepts of "coercion" and "undue influence" in determining when research participation is voluntary. Acknowledging structural coercion shifts the frame of ethical deliberation away from specific individuals and specific studies to see important patterns in research participation by salient demographic characteristics. The effects of structural coercion manifest themselves in particular research settings, but unlike the conventional form of coercion, it is not rooted in the researcher-participant relationship or linked to particular study protocols. By extracting voluntariness from entrenched conceptions of the researcher-participant dyad, this paper proposes approaches to minimize the effects of structural coercion while creating new ethical imaginaries for review boards and researchers alike.