This represents a competitive renewal of a major portion of NIDA contract N01DA38200. The portion of N01DA38200 being renewed herein, the entire contract (NIDA contract 271-90-7200) which preceded it, and several previous contracts dating back 19 years have focused on the generation of data related to the pharmacological properties and abuse liability profiles of a large number of opioid agonist, antagonist, and mixed agonist/antagonist agents. This project represents an extension of a search for potent analgesics with reduced abuse potential. In addition, data generated by this project are part of the scientific database used in decisions pertaining to scheduling of drugs under domestic laws (Controlled Substances Act) and international treaties (Single Convention and Psychotropic Convention). In brief, the objectives of this contract are: (1) to evaluate the antinociceptive activity of test compounds in mice; (2) to evaluate the effects of test compounds in opiate-dependent rats and/or monkeys; (3) to evaluate the intrinsic physical dependence capacity of test compounds in drug-naive monkeys; add (4) to assess the reinforcing properties of test compounds in monkey self-administration studies. The anticipated end results of this contract are written reports detailing the findings.