The experimental techniques and the prediction procedures for the determination or evaluation of the vapor pressure of environmentally relevant organic compounds are described; with 259 references examined. For each of them the characteristics of precision and accuracy are given, when available from the literature. The experimental methods are classified as “direct” and “indirect.” The first class includes all those which can measure directly the vapor pressure, while the second concerns those which need “known” vapor pressures of reference compounds for the calibration. Prediction methods are based on the application of the Clapeyron–Clausius equation or on the quantitative structure-property relationships. Also correlation methods require a suitable calibration. The vapor pressures at ambient temperature for several polycyclic aromatic hydrocarbons, polychlorinated biphenyls, polychlorinated dibenzo-p-dioxins and furans, selected pesticides, and some reference compounds are tabulated together with the vapor pressure equations and the enthalpy values in the temperature range of measurement. A critical comparison, based on a statistical analysis of the data obtained with different methods and derived from 152 references, is also carried out. ©1996 American Institute of Physics and American Chemical Society.