The ability to measure reactive isocyanate-containing compounds in air is important for assessing worker exposures in a variety of processes that produce or use surface coatings, polyurethane foams, adhesives, resins, elastomers, binders and sealants. Selecting the most appropriate sampling and analytical method for isocyanates in a specific workplace environment is difficult because isocyanates may be in the form of vapors or aerosols of various particle sizes; the species of interest are reactive and, therefore, unstable; pure analytical standards exist only for monomeric isocyanates; and low limits of detection are needed. As a result, errors can be introduced during numerous points in the sampling and analytical procedures. If an inappropriate method is selected, the result can be either a gross underestimation of the exposure or a failure to detect airborne isocyanates. Therefore, the ability to select the best method is critical for an accurate assessment of the worker's isocyanate exposure.