Drug dependence is often characterized by severe drug seeking behavior. Learning to understand, predict, and control this maladaptive choice behavior may lead to improved prevention and treatment strategies. HYD is a drug that is currently used as a cough suppressant and to relieve pain. The purpose of this study is to determine the extent to which opioid drug seeking behavior by heroin dependent individuals can be reduced by environmental factors, including supplemental opioid drug availability, drug price, and alternative non-drug reinforcers. Specifically, this study will determine whether knowledge of post-session HYD availability influences drug seeking behavior in heroin dependent individuals, who are maintained on buprenorphine during their participation.