This paper identifies various uses of the formulary concept, outlines factors that underlie the need for such an administrative device, and reviews four barriers to effective formulary control. It then examines selected components of the formulary system and specifies the need for supporting techniques, both internal and external. Twelve guidelines for developing a model drug formulary are presented. While administrative elements associated with implementation of a formulary are stressed, concerns about more intangible behavioural forces are introduced.