It was founded in 1893 by Charles T. Main, an engineer for the textile mills of New England. It was privately owned by its senior engineers, it being felt that this would leave decision making to those that knew the industry best. In addition to the then-traditional business of water and steam power, Main soon expanded into the new field of water resource engineering and hydroelectric generation. In 1949 it began an association with the United States Atomic Energy Commission working on projects relating to plutonium-based nuclear reactors. It rose to become a worldwide player in the utility industries, providing many wide-ranging engineering services. For example, in the mid-1950s Charles T. Main was responsible for the building of a hydro-electric plant in Turkey (Sarıyar Dam).