Current strategies to control photochemical air pollution rely on abating the emission of volatile organic compounds. Primarily, these compounds exist in the vapor phase, and are those with a carbon number of ten or less. Recent attention has been given to low-volatility organic compounds (LVO) which may be partitioned between the gas and aerosol phases, and may only partially participate in smog formation. A three-part study was conducted to determine the role of such LVO's. First, a comprehensive review was made of the existing literature on atmospheric LVO to evaluate existing data and the measurement techniques used to collect the data. Second, an effort was made to develop an 'estimator' for the phase distribution of LVO's in the atmosphere. The concurrent third part of the study involved an attempt to develop and test an improved and reliable collection and analysis technique for LVO. An effective denuder device was developed which can be used to provide a sample of the aerosol fraction of LVO under laboratory conditions.