A review is presented of a vapor-phase growth method that has been developed for the synthesis of a broad spectrum of III–V compounds. The predominant feature of this technique is the use of gases as the source chemicals, thereby providing improved control of the chemical composition, homogeneity, crystalline perfection, and impurity concentrations and distributions of the epitaxial layers. As a result, a number of notable advances have been made with respect to the material properties and device utilization of several III–V compounds. The chemistry of the deposition processes was studied by means of a mass spectrometer coupled to the vapor-phase growth system. Results of these studies are presented and discussed.