Pilot plants are a generic term covering numerous types of special equipment and systems designed to support or conduct research activities on a scale larger than glassware in a hood. This article briefly covers some of the principal topics and concerns and provides references for further information. Included are some different methods of categorizing pilot plants as well as information about typical units. The importance of scale‐up and planned experimentation are reviewed. The article discusses some of the more common concerns, highlighting the way pilot plants differ from commercial plants. Subjects include design, costs, schedules, and space. Control and instrumentation are also briefly covered. The importance and difficulty of start‐up is noted as is the difficulty of ensuring safety in such atypical equipment and operations.