Phase I clinical trials test the safety and tolerability of new pharmaceuticals and typically pay healthy people to enroll as research participants. In addition to being exposed to the risks of taking investigational drugs, healthy volunteers are confined to residential research facilities for some portion of the clinical trial. Most healthy volunteers are African American and Hispanic men in their late twenties to early forties. Motivated by pervasive economic insecurity and racial discrimination, these individuals often enroll serially in Phase I trials to stay afloat or to get ahead. This book reveals not only the social inequalities on which Phase I trials rest, but also depicts the important validity concerns inherent in this mode of testing new pharmaceuticals. Healthy volunteers are enrolled in highly controlled studies that bear little resemblance to real-world conditions. Moreover, in these studies everyone—from the pharmaceutical companies sponsoring the studies, to the clinics conducting them, and the healthy volunteers paid to participate—is incentivized to game the system, with the effect that new drugs appear safer than they really are. Providing an unprecedented view of the intersection of US racial inequalities with pharmaceutical testing, Adverse Events calls attention to the dangers of this research enterprise to social justice and public health.