Although there is scientific consensus that genetic factors play a substantial role in an individual's vulnerability to drug or alcohol addiction, specific genetic variables linked to risk or resilience remain elusive. Understanding how genetic factors contribute to addiction may require focusing on intermediary mechanisms, or intermediate phenotypes, that connect genetic variation and risk for addiction. This book offers a comprehensive review of this mechanistic-centered approach and the most promising intermediate phenotypes identified in empirical research. The contributors first consider the most established findings in the field, including variability in drug metabolism, brain electrophysiological profiles, and subjective reactions to direct drug effects; they go on to review highly promising areas such as expectancies, attentional processing, and behavioral economic variables; and finally, they investigate more exploratory approaches, including the differential susceptibility hypothesis and epigenetic modifications. Taken together, the chapters offer a macro-level testing of the hypothesis that these alternative, mechanistic phenotypes can advance the understanding of genetic influences on addiction. The book will be of interest to researchers and practitioners in a range of disciplines, including behavioral genetics, psychology, pharmacology, neuroscience, and sociology.Contributors: John Acker, Steven R.H. Beach, Gene H. Brody, Angela D. Bryan, Megan J. Chenoweth, Danielle M. Dick, Eske D. Derks, Mary-Anne Enoch, Meg Gerrard, Frederick X. Gibbons, Thomas E. Gladwin, Mark S. Goldman, Marcus Heilig, Kent E. Hutchison, Hollis C. Karoly, Steven M. Kogan, Man Kit Lei, Susan Luczak, James MacKillop, Renee E. Magnan, Leah M. Mayo, Marcus R. Munafò, Daria Orlowska, Abraham A. Palmer, Danielle Pandika, Clarissa C. Parker, Robert A. Philibert, Lara A. Ray, Richard R. Reich, Ronald L. Simons, Courtney J. Stevens, Rachel E. Thayer, Rachel F. Tyndale, Tamara L. Wall, Reinout W. Wiers, Michael Windle, Harriet de Wit