An overview is given of the physical phenomena that are affected by the gravitational environment found in low earth orbit. These phenomena are related to specific classes of materials that may benefit from microgravity processing, including biotechnological materials, semiconductors and crystals, metals and alloys, polymers, glasses, and fundamental fluid dynamic research. Examples are given of experimental results and potential applications for commercial development. The growth of commercial interest in microgravity processing within the United States is reviewed, with projections of future development scenarios. The status of domestic and international programs is summarized, including an overview of Japanese and European Spacelab and Soviet Salyut and Mir research. The role of Space Shuttle systems and plans for a materials laboratory on the Space Station is described.