This chapter discusses how new psychotropic drugs are approved for clinical use. While the FDA regulates other therapeutics such as biologics, over-the-counter drugs, and medical devices, the chapter provides an overview of the FDA's regulation of prescription drug products. The FDA's authorities are largely devoted to pre-marketing and post-marketing risk-benefit evaluation. An investigational new drug (IND) is used in a clinical investigation. The IND is unique to the regulatory process for drug approval. Center for Drug Evaluation and Research (CDER) classifies New Drug Applications (NDAs) with a code that reflects both the type of drug being submitted as well as the intended use. To monitor the safety of marketed drugs, the FDA maintains a complex system of postmarketing surveillance and risk-assessment systems to investigate the occurrence of serious and unexpected adverse drug experiences. The FDA's Adverse Event Reporting System (AERS) is an important drug safety tool.