Bethany was first settled in 1717 but it was not until May 1832 that Bethany separated from Woodbridge to become incorporated as a town.
There have been inhabitants in Bethany since before 1638, predominantly Naugatucks of the Paugusset Tribe and Mattabessitts of the Wanguck Tribe. The first European settlers arrived in the area around April 1638, creating the towns of Milford and New Haven, with their boundary split down the middle of what is now Bethany. The area of the boundary was settled in 1678, 12 years after New Haven County was organized. In 1717, the Amity Parish was accepted by the General Assembly of the Connecticut Colony and in 1832, Bethany was incorporated as a town. In the mid-to-late 19th century, the population of the town and the land decreased as parts were annexed by the neighboring town of Woodbridge and the new town of Beacon Falls was incorporated into the general geography of Connecticut.
Bethany Probate District covers Town of Bethany. Constituted 4 July 1854 from New Haven.