Caffeine and Cocaine

Inclusion Criteria: * Subjects who currently meet DSM-IV criteria for cocaine dependence and healthy controls * At least one cocaine positive urine during screening. * Current regular consumption of caffeine. * Female subjects: a negative pregnancy test. Exclusion Criteria: * Current or past DSM-IV Axis I disorder other than substance abuse/ dependence * Any significant non-psychiatric medical illness requiring ongoing medical treatment or which would preclude treatment with d-amphetamine or caffeine * Substance dependence other than cocaine within the last 3 months. * Positive breath alcohol. * Positive urine drug screen for drugs other than cocaine or THC at the time of behavioral testing * For female subjects: known pregnancy or a positive pregnancy test or current breast feeding. * Diagnosis of Adult Attention Deficit Disorder as determined by: a) meeting DSM-IV criteria for childhood ADHD, b) currently has impairing ADHD symptoms, c) ADHD symptoms can not have remitted at any period since childhood. * HIV positive. * I.Q. below 70.