The explosive growth of compound semiconductors into the fields of electronic and optical devices has been due to the development of advances epitaxial growth techniques. These epitaxial techniques have proved capable of producing high purity materials in ultra-thin multi-layer structures. The metal-organic vapor phase epitaxy (MOVPE) technique is emerging as the technique of choice in many applications to produce such exacting structures. The growth of epitaxial materials in the MOVPE technique is typically accomplished by the co-reaction of reactive metal alkyls with a hydride of the non-metal component. A diversity of chemical growth precursors and growth system designs has allowed for the successful growth of a large number of materials and structures, despite the complex nature of the growth process. This review will explore the recent advances in the understanding of the interactions within the growth environment; the coupled thermal, fluid, and chemical environments. These interactions determine the growth and physical properties of the deposited materials. In particular, the nature of the chemical reactions taking place on or near the growth surface can dominate the material's electrical and chemical properties. Alterations in the growth chemistry have been shown to be an effective means of influencing both the material's purity, through the incorporation of unintentional impurities, and utility, by the controlled incorporation of electrically active impurities or dopants. Some of the practical aspects in the growth of materials and the effective design of growth systems will also be presented. © 1987.