Participants will be randomized to one of two groups: propranolol (40 mg, oral, immediate-release formulation) or placebo. The study will include four laboratory sessions: (1) An information-gathering session that includes an interview to obtain information for development of a personalized drug script/cue set. (2) A two-hour intervention session in which there will be baseline measures, drug administration (propranolol or placebo, double blind), and, starting 60 min after drug administration, two script-guided imagery sets. Cue-responsivity data will be collected, but the main purpose of the session is interventional. This will be the only administration of propranolol during the study. (3, 4) Two follow-up test sessions, 1 and 5 weeks after the intervention session; participants responses to re-exposure to the personalized drug script/cue set will be measured. In addition to attending the four laboratory sessions, participants will make brief visits to our outpatient clinic for twice-weekly monitoring of ongoing drug use via urine screens and self-report, starting 1 week before the intervention session and ending 5 weeks later.