The uses and selection of equipment for engineering control monitoring were reviewed. The purposes for which control monitoring instrumentation can be used were listed. The role of control monitoring in workplace control was discussed, and the need to view control monitoring systems as an integral part of the workplace control system was emphasized. The three main components of a control monitoring system, the sampling component, the analyzer or detector, and the data acquisition and display component, were described. Applications of control monitoring were illustrated by a number of examples from various industries such as plastics, resins, textiles, lead battery manufacture, parking garages, steel production, and electronic component manufacture. Factors which should be considered when selecting equipment for control monitoring applications were discussed: required sampling component, minimum detectable limit, required dynamic range, time constant, workplace constraints (temperature, humidity, hazardous location classification), type of data acquisition and display required, interferences, personnel for operation and maintenance, and costs (direct and operating). The author concludes that control monitoring systems have already demonstrated their effectiveness in controlling and monitoring exposure of workers to hazardous substances, and that such systems are of great value providing equipment is chosen properly.