Occupational exposure to styrene (100425) in the reinforced plastic boat building industry (SIC-3732) was studied. Seven facilities were included in the study. Full shift time weighted average (TWA) occupational exposures to styrene were measured. Parameters for selection of facilities were boat size, production rate, and number of employees. The facilities were surveyed for 3 days. Charcoal tubing sampling was used to collect exposure samples. A total of 297 TWA personal breathing zone air samples were collected on workers in four key jobs: hull laminating, deck laminating, small parts laminating, and gel coating. Mean exposure in hull lamination ranged from 35.0 to 122 parts per million (ppm). Deck lamination exposure ranged from 37.2 to 124ppm. Small parts lamination exposure ranged from 29.7 to 97.2ppm, and gel coating exposure ranged from 12.2 to 65.2ppm. Styrene concentrations in 234, or 59 percent, of the personal samples exceeded the NIOSH recommendation of 50ppm, and 96, or 24 percent, exceeded the OSHA TWA limit of 100ppm. The mean exposures measured in the four categories were significantly different from each other. Hull and deck lamination formed a higher exposure group, and small parts and gel coating formed a lower exposure group. These jobs appeared proportional to resin consumption. Styrene suppressed resins were used. Exposure control was primarily ventilation. Dilution ventilation appeared to be the most promising approach. The determinants of exposure were part size configuration and surface area. The authors conclude that reduction of styrene exposure will result if dilution ventilation is used in combination with local ventilation, use of styrene suppressed resins, and the introduction of work practice guidelines.