Recent publicity given to so-called "toxic mold" has raised the concerns of many in the HVAC industry -- and for good reason. Mold, an indoor issue since at least biblical times, has exploded onto the national litigation scene in a manner reminiscent of other materials, most notably asbestos, that led to thousands of legal claims, the expenditure of an enormous amount of resources and many bankruptcies. This column will briefly describe some of the factors that are creating the potential for a large number of lawsuits and then will describe some of the ways practitioners can try to prevent becoming entangled in these cases or at least limit their liability.