This chapter describes some of the practical methods which have been suggested for the production and storage of commercial vesicular-arbuscular mycorrhizae (VAM) inoculum. It indicates some of the common mechanisms which have been shown to inhibit or improve the production and storage of VAM inoculum. The chapter outlines the theory and principles for producing and storing consistently high-quality, disease-free VAM inoculum. The production of VAM inoculum has evolved from the original use of infested field soils or sievings from these soils, to the use of soil and roots of greenhouse plants inoculated with field inoculum, to the current practice of using pot culture inoculum derived from surface-disinfested spores of a single VAM fungus on a host plant grown in a sterilized growth medium. The most important aspect of VAM inoculum production may be the selection of an appropriate growth medium. Phosphorus is usually considered to be the major problem when VAM infection is poor.