The purpose of the NIMH Chemical Synthesis and Drug Supply Program is to synthesize, purify, and provide essential compounds that are unavailable from commercial sources (e.g., the stock has been depleted and it will not be replenished, patented compounds that are unavailable while undergoing clinical trials, etc.) to stimulate basic and clinical research relevant to mental health in areas such as the molecular pharmacology and signaling of CNS receptors, longitudinal studies to evaluate the molecular, biochemical, and behavioral actions of psychoactive compounds, and functional brain imaging in primates and humans. The present initiative focuses on the synthesis of current GMP (Good Manufacturing Practices) and non-GMP compounds for basic and clinical research such as novel central nervous system receptor subtype-selective agonists and antagonists, radiolabeled compounds, and novel PET, SPECT, and fMRI ligands for functional brain imaging.