The Food and Drug Administration (FDA) oversees the approval and regulation of drugs entering the U.S. market. Two regulatory frameworks support the FDA’s review of prescription drugs. First, FDA reviews the safety and effectiveness of new drugs that manufacturers wish to market in the United States; this process is called pre-market approval or pre-approval review. Second, once a drug has passed that threshold and is FDA-approved, FDA acts through its post-market or post-approval regulatory procedures. This book is a primer on drug approval and regulation. It describes how drugs are approved and come to market, including the FDA’s role in that process and the FDA and industry roles once drugs are on pharmacy shelves.