The simple fact that the authors were able to give injectable heroin to volunteers for addictive self-administration at a Harvard facility may elude the notice it deserves. On the other hand, resec:irch questions center­ ing on whether heroin is linked to a craving for pleasure or relief of pain might raise the transplanted hackles of those who simplistically see scien­ tists as pursuing only transparent trivialities. In truth, this report is about a historical and pioneering step in clinical research on a major unsolved problem of the biological-social-psychological roots of addiction. The research questions posed are clearly relevant both to the design of effec­ tive treatments (and treatment policy) and to the basic science search that could help our understanding of how addictive drugs capture such power­ ful control over behavior. Heroin was synthesized and has been available, along with aspirin, for over three-quarters of a century. Yet with all the tools of Western sci­ ence, and with the enormous and growing social, personal, and economic costs of world-wide heroin use, we-surprisingly--