Spores, active or dormant, are ubiquitous. Although it is impossible to get rid of all the spores, fungal growth can be controlled. Conditions must be maintained that will prevent the growth of active spores or the revival of dormant ones. Although the conditions governing the latter are poorly understood, it is advisable to avoid temperature extremes and exposure to chemicals except when absolutely necessary for the preservation of the material. Most important for mold control is maintaining relative humidity (RH) conditions below 55%, or, better, below 45%. Use of protective enclosures, meticulous housekeeping, monitoring of RH and temperature, and a watchful eye are also important. If resources allow, high-level filtration of storage areas, if not of the whole building, is recommended. Protecting library and archival collections from water accidents should be among the highest priorities for any institution. Wet collections must be immediately dried or stabilized by freezing. Moldy materials must be isolated, dried if wet, then cleaned using the strictest precautions. In a library or archive a silent invasion of mold is always a cause for consternation. Fortunately there are ways to prevent it, with knowledge, care and, above all, vigilance. -- AATA