Wassaic is located in southeast New York, surrounded by the East and West Mountains and along the Tenmile River.
The name of the hamlet means Washaic, or "land of difficult access," by the Indigenous Americans.
Wassaic is home to The Wassaic Project, a non-profit arts and music organization and the Wassaic Artist Residency. They provide summer programming as well as run an artist in residence program.
Wassaic's main employers in the 19th century were Gridley Iron Works and the Harlem division of the New York Central Railroad. In 1861 Gail Borden opened a factory for producing a milk that would not need refrigeration. Today, it is known as Borden's Eagle Brand Condensed Milk. Wassaic was also known for dairy sheep and grain farming.