The National Institute for Occupational Safety and Health (NIOSH) conducted an industrial hygiene study of workers exposed to styrene monomer in the fiberglass reinforced plastic boat industry. This industry was chosen for study because of its length of operation and the high styrene monomer exposures experienced by these workers. The objective of the study was to provide extent of exposure data for specific jobs by including plants representing a cross-section of the industry. Industrial hygiene surveys were conducted at seven plants. Overall exposure to styrene monomer ranged from 2 parts per million (ppm) to 183 ppm. Mean exposures for the four primary job categories of hull lamination, deck lamination, small parts lamination and gel coating were found to be 78 ppm, 67 ppm, 44 ppm and 48 ppm respectively.