Ephraim left his sizeable estate to support the founding of a free school on his land in western Massachusetts, on the conditions that the town be renamed after him (Williamstown, Massachusetts, formerly West Hoosac), that the town be part of the Massachusetts Bay Colony, and that the free school be built on the land which he donated. He previously intended to found the school as an academy for "the Promoting & propogating Christian knowledge amongst the Indians at Stockbridge" but was deterred by the potential of the project being manipulated by his political rivals after his death. The school was founded in 1791 and converted to Williams College by action of the state legislature in 1793.