The first section of the monograph contains the biography and accomplishments of Horace H. Loh, the recipient of the 2002 Nathan B. Eddy Memorial Award for his studies on the molecular mechanism of opioid tolerance, i.e., receptor desensitization and phosphorylation. This section of the monograph also contains the introduction of the Marian W. Fischman Memorial Award and its first recipient, Dr. Chris-Ellyn Johanson. The second and core section of this monograph summarizes the content of 16 symposia. One symposium focused on the importance of systems other than dopamine in the reinforcing/neurochemical effects of psychostimulants. Another symposium considered substance abuse, immunomodulation, and infection; and a third symposium considered the mediating role of parental cognitions in the parenting processes of drug-dependent mothers and fathers. Other symposia addressed the rewards to drug abusers offered by dopamine, the medical consequences of drug dependence, prescription drug abuse, the characteristics of cocaine addiction, the status and implications for prevention of longitudinal studies of pathways to drug abuse, and drugs and crime. Remaining symposia considered the relationship between exposure to violence and substance abuse, neuropeptidergic responses to psychostimulant drugs of abuse, the application of information technologies to drug abuse prevention and treatment, the French experience with buprenorphine, and what is known and needs to be known about drug choice. A third section of the monograph presents annual reports on four research programs, and the concluding section reports on a workshop on medications development sponsored by the National Institute on Drug Abuse. Author and subject indexes