The focus of this review is primarily on recent developments in bidirectional translational research on the addictions, within the Laboratory of the Biology of Addictive Diseases at The Rockefeller University. This review is subdivided into major interacting aspects, including (a) Investigation of neurobiological and molecular adaptations (e.g., in genes for the opioid receptors or endogenous neuropeptides) in response to cocaine or opiates, administered under laboratory conditions modeling chronic patterns of human self-exposure (e.g., chronic escalating "binge"). (b) The impact of such drug exposure on the hypothalamic-pituitary-adrenal (HPA) axis and interacting neuropeptidergic systems (e.g., opioid, orexin and vasopressin). (c) Molecular genetic association studies using candidate gene and whole genome approaches, to define particular systems involved in vulnerability to develop specific addictions, and response to pharmacotherapy. (d) Neuroendocrine challenge studies in normal volunteers and current addictive disease patients along with former addicts in treatment, to investigate differential pharmacodynamics and responsiveness of molecular targets, in particular those also investigated in the experimental and molecular genetic approaches as described above.