Abstract: Drug formularies have existed since the 1940s. The formulary in any health system is not a static list of drugs; it is not a "light switch" or a "yes" and "no" system. The formulary is part of a system for quality drug therapy within that system. The formulary in hospitals and large systems is established by the Pharmacy and Therapeutics Committee (or similar body) by a medical staff committee establishing policies for the effective, safe, and cost-effective use of drugs. Overall, a formulary should meet the needs of individual patients based on the best available evidence. The formulary is part of quality improvement and education programs within a health system.