The primary aim of our research is to delineate the role of dopamine in motivated behavior with a special emphasis on the long-term effects of early life (adolescent) drug use on learning and decision making. Adolescent alcohol use is a major public health concern and is strongly correlated with the development of alcohol abuse problems in adulthood. The phasic activation of the neuromodulator dopamine is implicated in reward processing, decision making, and many aspects of drug abuse. Thus, we use a combination of experimental approaches, including in vivo fast-scan cyclic voltammetry, to examine the link between a history of alcohol use in adolescence, perturbation of dopamine systems, and deficits in decision making and learning that may represent vulnerabilities to the development of addictive disorders.