This chapter discusses the global markets in which the primary plant disease control chemicals, the fungicides, are required and the factors that sustain their use. It reviews the discovery and safety testing process, the benefits and risks from use and nonuse, as well as integrated control approaches to sustain and maximize the utility of these important crop production tools. Fungicides are chemical products active in controlling pathogens which damage or destroy plants. In the 1970s new chemical classes of fungicides were discovered that control fungi by inhibiting biosynthesis of fungal sterols. A simple model of fungicide dynamics illustrates the challenge of determining how much chemical to apply and how often to make applications. Effective and reliable disease control is only one of three necessary attributes of plant disease control chemicals. The primary goal in the discovery of a new fungicide is to create a product that provides a solution to a farmer’s disease problems.